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Melanocytic tumors

6  Skin tumors

6.6  Melanocytic tumors

Introduction:

Benign melanocytic tumors (melanocytic nevi) and malignant tumors (malignant melanoma, melanoma, melanoblastoma) are tumors of melanocytes, cells of neuroectodermal origin. These cells enter the epidermal basal layer during embryonal development. Later produce melanin, brown pigment, which is taken up by surrounding melanocytes. Melanin stains the epidermis brown and protects the body against UV radiation.

In normal skin the melanocytes are regularly dispersed within the basal layer of the epidermis. Their cytoplasm is pale and nuclei have fine chromatin.

For details concerning pathology of melanocytic lesions refer to the specialized literature.

6.6.1  Melanocytic nevus

6.6.1.1  Common melanocytic nevi

Clinical signs:

  • location: anywhere on the body, some are present at birth, most of them appear during childhood and puberty
  • macules, papules of different shades of brown, sometimes pink or dark blue
  • the surface is smooth, some lesions are pedunculated, some wiht hairy
  • so called dysplastic nevi are of irregular borders, variable color (even red) and can be multiple

Pictures

Melanocytic nevi:
Melanocytic nevus, CLINIC (1102)

Melanocytic nevi on the back:
Nevus, CLINIC (847)

Melanocytic nevi on the back, so called dysplastic:
Melanocytic nevus, CLINIC (1104)

Further examples of melanocytic nevi:

6.6.1.1.1  Lentigo simplex

Clinical signs:

  • flat, pigmented macule
  • size: several millimeters

Pictures

Examples of simple lentigo:

Histology:

Epidermis with increased number of melanocytes in single units, often hyperpigmented. Rete ridges are elongated. No melanocytes within the dermis, but melanophages are often present. Slight lymphocytic infiltrate is common.

Pictures

Lentigo simplex:
Lentigo simplex, HE 40x (2575)

Lentigo simplex:
Lentigo simplex, HE 20x (5348)

Lentigo simplex:
Lentigo simplex, HE 60x (10679)

6.6.1.1.2  Junctional melanocytic nevus

Clinical signs:

  • flat or slightly raised, pigmented macule, sometimes multiple
  • well circumscribed

Histology:

Melanocytes in single units and in nests are limited to the lower part of the epidermis. No melanocytic atypia. No melanocytes within the dermis, but melanophages are often present. Slight lymphocytic infiltrate is often present.

Pictures

Junctional melanocytic nevus:
Melanocytic nevus, junctional, HE 40x (2307)

Another case:
Melanocytic nevus, junctional, HE 40x (2729)

Another case:
Junctional melanocytic nevus, HE 40x (3510)

Another similar nevus of the same patient:
Melanocytic nevus, junctional, HE 40x (3525)

Junctional melanocytic nevus of the sole:
Melanocytic nevus, junctional, HE 60x (6374)

Combination of junctional nevus and seborrhoic keratosis:
Melanocytic nevus and seborrhoic keratosis, HE 20x (13681)

6.6.1.1.3  Compound melanocytic nevus

Clinical signs:

  • variably pigmented papule
  • size varies, from milimeters to many centimeters
  • the surface is sometimes hairy
  • different types: flat papules (esp. on the back), polypoid lesions (abdomen, lateral aspects of the trunk), firm, domed papules (face)

Histology:

Melanocytic lesion with junctional part (intraepidermal nests) and dermal part (dermal nests of melanocytes). The dermal melanocytes usually mature (their size decreases downward, sometimes neuroid transformation is present). The lesion is symmetric, borders are sharp.

Nevi on palms or soles (acral nevi) can have some melanocytes scattered intraepidermally. Transcutaneous elimination of pigment is regular (columns) and lateral borders are sharp.

6.6.1.1.4  Dermal nevus

Clinical signs:

  • papule, variably pigmented
  • size variable

Histology:

Melanocytes in nests, strands and as single units within the dermis. Their shape is roudnish or cuboid, cytoplasm well defined, nuclei are roundish or oval, pale, chromatin is fine. Multinuclear melanocytes are sometimes found. The amount of melanin is variable.

Deepest areas of the nevus are composed of elongated melanocytes; their chromatin is fine. The amount of melanin is low or no melanin is present at all.

Neuroid transformation is sometimes present.

The amount of melanophages is variable.

Pictures

Intradermal melanocytic nevus:
Melanocytic nevus, intradermal, HE 60x (13291)

Dermal nevus:
Melanocytic nevus, intradermal, HE 40x (2306)

Another case:
Melanocytic nevus, intradermal, HE 40x (2577)

Another case:
Dermal melanocytic nevus, HE 60x (10881)

Another case:
Melanocytic nevus, intradermal, HE 60x (10915)

Another case:
Melanocytic nevus, intradermal, HE 40x (10940)

Another case:
Melanocytic nevus, intradermal, HE 60x (12713)

Intradermal melanocytic nevus with clonal proliferation:
Dermal clonal melanocytic nevus, HE 40x (10892)

Intradermal melanocytic nevus with neuroid maturation:
Intradermal melanocytic nevus with neuroid maturation, HE 20x (13216)

Intradermal melanocytic nevus with neuroid maturation, polypoid:
Intradermal nevus with neuroid differenciation, HE 40x (12714)
Melanocytic nevus with neuroid maturation, HE 40x (12489)

Intradermal melanocytic nevus:
Intradermal nevus with neuroid differenciation, HE 40x (12715)

Intradermal melanocytic nevus, papillomatous:
Intradermal melanocytic nevus, papillomatous, HE 60x (12490)

Another case, with tiny osteoma:
Intradermal melanocytic nevus, HE 60x (10845)

Intradermal melanocytic nevus with minimal pigment production and verrucous surface:
Melanocytic nevus, intradermal, HE 20x (4294)  [zoomify]

Intradermal melanocytic nevus with papillomatous surface:
Papillomatous melanocytic nevus, HE 40x (10893)

Dermal nevus with neuroid differentiation:
Melanocytic nevus, intradermal, HE 40x (2305)

Traumatized dermal melanocytic nevus:
Melanocytic nevus, traumatized, HE 40x (2579)

Melanocytic nevus with fat tissue:
Melanocytic nevus, intradermal, lipomatous, HE 20x (4805)  [zoomify]

Another case of a nevus with fat (old fatty nevus):
Melanocytic nevus, intradermal, with fat, HE 40x (5133)  [zoomify]

Another case of a nevus with fat:
Melanocytic nevus, intradermal, with fat, HE 60x (13367)

Intradermal melanocytic nevus with many multinuclear melanocytes:
Melanocytic nevus, intradermal, with multinuclear melanocytes, HE 40x (12922)

Intradermal melanocytic nevus under seborrhoic keratosis:
Intradermal melanocytic nevus under seborrhoic keratosis, HE 20x (13749)

Flat seborrhoic keratosis:
Seborrheic keratosis, flat, HE 40x (12569)

Intradermal melanocytic nevus with teleangiectasias or combined with capillary hemangioma:
Hemangioma, n. teleangiectaticus, HE 60x (10780)

6.6.1.1.5  Speckled lentiginous nevus, nevus spilus

Clinical signs:

  • brown macule with dark, hyperpigmented spots
  • sometimes widespread or segmental
  • age: congenital lesion

Histology:

Small junctional or compound nevi on the lentiginous background.

6.6.1.2  Balloon cell nevus

Clinical signs:

  • histological variant of a melanocytic nevus

Histology:

Large melanocytes with broad, pale cytoplasm and small, dark regular nuclei. Other properties correspond to common melanocytic nevi (symmetry, sharp borders). Multinuclear melanocytes are sometimes present.

6.6.1.3  Halo nevus

Clinical signs:

  • often appear after sun tanning, rarely sign of a melanoma
  • roudish depigmented papule surrounding melanocytic nevus
  • melanocytic nevus ofter involutes
  • development: repigmentation, sometimes vitiligo

Pictures

Halo nevus, remnants of a melanocytic nevus in the middle:
Nevus halo, CLINIC (748)

Halo nevi of Sutton:
Melanocytic nevus, CLINIC (1103)

Halo nevus:
Nevus halo, CLINIC (749)

Another case:
Halo nevus, CLINIC (2977)
Halo nevus, CLINIC (2978)

Halo nevi are sometimes combined with vitiligo:
Vitiligo, CLINIC (3428)
Vitiligo, CLINIC (3429)
Vitiligo and halo nevus (Sutton), CLINIC (3430)

Histology:

Dense lymphocytic infiltrate surrounding remnants of a melanocytic nevus. Sometimes only scattered melanocytes and pigment within melanophages remain.

6.6.1.4  Melanocytic nevus with clonal proliferation

Clinical signs:

  • nevus with nodules, often darker

Histology:

In benign looking nevus there are nodules of larger, roundish melanocytes, without mitotic activity. HMB45 may be positive.

6.6.1.5  Eczematized melanocytic nevus

Clinical signs:

  • common nevi develop erythematous reaction

Histology:

Common nevus with inflammatory infiltrate with eosinophils.

Case study:

Meyerson's nevus
MUDr. Hana Jedličková, PhD.

Introduction:

This type of nevus was described in 1971 by L. B. Meyerson (A Peculiar Papulosquamous Eruption Involving Pigmented Nevi). His patients were two young men with inflammatory papulosquamous changes of their melanocytic nevi. The inflammation healed after several months, leaving the nevi intact.

Histologically a melanocytic nevus is found with changes as parakeratosis, focal spongiosis, acanthosis and lymphocytic perivascular infiltrate with eosinophils.

The etiology is unknown, Koebner phenomenon in pityriasis rosea was suggested, and on the other hand no association with atopy has been found. An upregulation of ICAM 1 was described.

The lesions can be solitary or multiple. The condition is more common in young men.

Meyerson phenomenon can occur also in seborrhoeic keratosis, dermatofibroma, basal cell carcinoma and squamous cell carcinoma.

Progression into halo nevus was described.

History:

29-year-old man had a history of returning inflammation of melanocytic nevi on his left upper extremity for approx. 6 years. He reported infrequent itching of other nevi on the trunk. He was otherwise healthy.

The inflammation always healed after several weeks; only topical corticosteroids were used.

One lesion was excised for histological examination.

Clinical signs:

The patient was phototype III. On his left arm he had a light brown nevus with an eczematous circle of 1 cm in diameter with yellow crusts and oozing. Similar but not so prominent changes were found in one other nevus. On the trunk he had two halo nevi and several pigmented nevi, some of them with red brown color.

Pictures

Meyerson's nevus:
Meyerson nevus, CLINIC (6155)

Histology:

In the centre of the lesion is a small compound nevus. Epidermis shows acanthosis and spongiosis extending significantly the nevus. In the spongiotic vesicles there are many lymphocytes and some eosinophils. Superficial inflammatory lymphohistiocytic perivascular infiltrate has an admixture of eosinophils.

Pictures

Eczematized melanocytic nevus of Meyerson:
Eczematized nevus, HE 40x (4148)

6.6.1.6  Recurrent melanocytic nevus

Clinical signs:

  • follows incomplete surgical removal (shave) of a former compound melanocytic nevus

Histology:

Junctional activity, often in irregular melanocytic nests over a layer of superficial dermal fibrosis (scar). Below the scar there is the remaining (persisting) intradermal part of the nevus. The area of junctional activity corresponds to the intradermal part (no lateral spread).

Pictures

Recurrent melanocytic nevus:
Melanocytic nevus, recurrent, HE 40x (2308)

Recurrent melanocytic nevus, scar:
Melanocytic nevus, recurrent, HE 60x (13680)

Recurrent melanocytic nevus, scar:
Melanocytic nevus, recurrent, HE 40x (12921)

Recurrent melanocytic nevus after laser therapy with melanocytic atypia:
Melanocytic nevus, recurrent, after laser therapy, HE 20x (5256)
Melanocytic nevus, recurrent, after laser therapy, Melan A 20x (5255)

Another case of recurrent melanocytic nevus after laser destruction:
Recurrent melanocytic nevus after laser destruction, HE 60x (6191)
Recurrent melanocytic nevus after laser destruction, HE 60x (6192)

Another case of recurrent melanocytic nevus after laser destruction:
Recurrent melanocytic nevus after laser burn, HE 60x (13850)

Melanocytic nevus after incomplete excision (this nevus is not recurrent, the excision was just made wider soon after primary biopsy):
Melanocytic nevus, intradermal, after incomplete resection, HE 40x (13364)

6.6.1.7  Melanocytic nevus on a skin graft

Introduction:

Small compound melanocytic nevus on a skin graft (the patient was combusted long time ago) with sclerotic corium of the graft.

6.6.1.8  Melanocytic nevus in pregnancy

Introduction:

Atypical changes can be seen in some melanocytic nevi during pregnancy. When the information about pregnancy is not passed to the pathologist, differential diagnostic problems against melanoma may arise.

Pictures

Melanocytic nevus in pregnancy:
Melanocytic nevus, pregnancy, HE 60x (6178)

Compound melanocytic nevus removed from the perineum during the delivery, showing activated melanocytes in perigenital area:
Melanocytic nevus, compound, perineum, removed at delivery, HE 60x (6398)

Melanocytic nevus in pregnancy:
Melanocytic nevus, gravidity, HE 60x (13305)

6.6.1.9  Giant melanocytic nevus

Clinical signs:

  • inborn melanocytic nevus
  • color: dark brown
  • size: large (many centimeters, may cover large areas of the body)
  • usually with fine hairs
  • benign, but melanoma may develop (even multilocular)

Pictures

Giant melanocytic nevus:
Melanocytic nevus, giant, congenital, CLINIC (3152)

Further examples of congenital nevi:

Histology:

Melanocytic nevus (compound or intradermal) composed of regular melanocytes. The melanocytes reach deep into the dermis, spread along the adnexa. Deep parts may show neuroid differentiation. Areas of a blue nevus may be present as well.

Cellular nodules of low mitotic activity may develop. Some of them may turn malignant (high atypia, high mitotic activity, necrosis).

6.6.1.10  Deep penetrating nevus

Clinical signs:

  • age variable (considered to be congenital)
  • face, upper trunk
  • usually pigmented

Histology:

Inconspicuos or none junctional nests, dermal nests and fascicles of melanocytes, reaching deep into the dermis (or subcutis). Deep part has usually oninon-like or dumbbell-like shape. S100+, HMB45+.

6.6.1.11  Nevus Spitz

Clinical signs:

  • nevus appears in any age, typically in children
  • pinkish, usually with little or no pigmentation

Histology:

Junctional, compound or dermal nevus, composed of epithelioid melanocytes (large, with broad, pink cytoplasm, sometimes multinuclear). Compound Spitz nevi show often mitotic activity.

Intraepidermal melanocytes are organized in nests and in single units and often epidermal scatter is present. Melanocytes are (at least focally) spindle-shaped, running parralelly. The amount of melanin is usually low. The extent of intraepidermal component does not extend beyond the dermal part. The melanocytes mature towards the base of the nevus.

Epidermis is hyperplastic, granular layer is focally increased. Eosinophilic globules (Kamino bodies) are sometimes present. Within the nevus is usually slight lymphocytic infiltrate.

The shape of the lesion is symmetric, the bottom is usually flat, lateral borders are sharp. Junctional nests of melanocytes are often separated by clefts from surrounding epidermis. Some Spitz nevi may be desmoplastic or show hyalinization.

Pictures

Nevus Spitz, dermal:
Melanocytic nevus, intradermal, Spitz, HE 40x (2369)

Nevus Spitz, dermal:
Melanocytic nevus, intradermal, Spitz, HE 60x (10188)

Nevus Spitz:
Melanocytic nevus, Spitz, HE 40x (2582)

Another case:
Melanocytic nevus of Spitz, HE 40x (4192)

Another case:
Melanocytic nevus, Spitz, HE 40x (5485)

Another case:
Spitz nevus, HE 60x (6250)

Another case:
Melanocytic nevus, Spitz, HE 60x (13256)

Junctional spindle cell melanocytic nevus of Spitz:
Melanocytic nevus, junctional, spindle cell (of Spitz), HE 40x (4293)  [zoomify]

Junctional melanocytic nevus of Spitz:
Junctinal melanocytic nevus of Spitz, HE 40x (10676)

Junctional melanocytic nevus of Spitz, Kamino bodies:
Melanocytic nevus, Spitz, HE 60x (13789)

Compound nevus Spitz:
Melanocytic nevus, Spitz, HE 20x (4891)  [zoomify]

Desmoplastic nevus of Spitz, HE, S100, CD68:
Melanocytic nevus, Spitz, desmoplastic, HE 20x (4460)  [zoomify]
Melanocytic nevus, Spitz, desmoplastic, S100 20x (4461)
Melanocytic nevus, Spitz, desmoplastic, HE 20x (4458)

Intradermal Spitz nevus:
Melanocytic nevus, intradermal, Spitz, HE 40x (6112)

Intradermal Spitz nevus:
Melanocytic nevus, intradermal, Spitz, HE 20x (5339)

Intradermal Spitz nevus, exophytic:
Melanocytic nevus, intradermal, Spitz, HE 20x (4987)  [zoomify]

Intradermal Spitz nevus of spindle cell melanocytes:
Melanocytic nevus, Spitz, HE 20x (4988)

Mostly intradermal Spitz nevus:
Spitz nevus, HE 40x (10894)

Mostly intradermal Spitz nevus:
Nevus Spitz, HE 40x (12717)

Compound nevus Spitz:
Melanocytic nevus, Spitz, HE 20x (4989)  [zoomify]

Compound nevus Spitz:
Melanocytic nevus, intradermal, Spitz, HE 60x (13964)
Melanocytic nevus, intradermal, Spitz, Melan A 60x (13965)

Compound nevus Spitz:
Melanocytic nevus, Spitz, HE 20x (4990)  [zoomify]
Melanocytic nevus, Spitz, HE 40x (10942)

Small compound pigmented Spitz nevus:
Melanocytic nevus, Spitz, pigmented, HE 20x (4991)

Traumatized Spitz nevus:
Melanocytic nevus of Spitz, traumatized, HE 20x (5415)

Recurrent Spitz nevus:
Recurrent Spitz nevus, HE 60x (13852)

Spitz nevus:
Atypical Spitz nevus, HE 60x (13440)
Atypical Spitz nevus, HE 60x (13439)
Atypical Spitz nevus, HMB45 20x (13437)
Atypical Spitz nevus, Melan A 20x (13438)

Epitheloid Spitz nevus:
Spitz nevus, epitheloid, HE 60x (14092)

Atypical Spitz nevus or spitzoid melanoma:
Spitz nevus or spitzoid melanoma, HE 40x (13217)

Atypical Spitz nevus with loss of BAP1 expression, girl, 7 years, forhead:
Atypical melanocytic nevus, Spitz, HE 60x (13982)

Atypical Spitz nevus with loss of BAP1 expression, girl, 11 years, neck:
Atypical melanocytic nevus of Spitz, BAP1 negative, HE 60x (13963)
Atypical melanocytic nevus, Spitz, HE 60x (14020)

6.6.1.11.1  Pigmented spindle cell nevus (Reed)

Clinical signs:

  • deeply pigmented acquired macule or flat papule
  • size about 5 mm
  • age: adults
  • location: often thigh

Histology:

Small, symmetric lesion, composed of heavily pigmented, spindle shaped, often vertically oriented melanocytes at the junction. Single melanocytes within upper areas of the epidermis may be present. Kamino bodies are sometimes present. Mitotic activity is common.

Pictures

Pigmented spindle cell nevus of Reed:
Melanocytic nevus spindlecell of Reed, pigmented, HE 40x (12942)

6.6.1.12  Blue nevus

Clinical signs:

  • inborn macules, patches or plaques, variable size
  • located intradermally, bluish color
  • some forms have typical location (nevus of Ota or Ito)
  • benign
6.6.1.12.1  Blue nevus of common type, of dendritic melanocytes

Histology:

Epidermis is normal. Intradermally many elongated, dendritic melanocytes spread between dermal collagen. Large amount of melanin is usually present within the melanocytes and within macrophages as well.

Superficial variant is limited to the upper half of the dermis, deep forms affect the whole thickness of the dermis and may reach into the subcutaneous fat.

6.6.1.12.2  Cellular blue nevus

Histology:

Blue nevus as in the common dendritic type, in addition with areas composed of roundish, nondendritic melanocytes with broad cytoplasm and low melanin production.

Melanocytes may have atypical nuclei and mitoses are sometimes present.

The tumor may reach deep into the dermis or subcutaneous fat.

6.6.1.12.3  Special forms of blue nevi

Clinical signs:

  • inborn lesions
  • mongolian spot: path in sacral area (inborn, usually disappears)
  • nevus of Ota: nevus fusoceruleus ophthalmomaxillaris
  • nevus of Ito: nevus fusoceruleus acromiodeltoidealis
  • dermal melanocyte hamartoma

Histology:

Scattered wavy dendritic melanocytes containing fine melanin granules; melanophages are not present.

6.6.1.12.4  Combined nevi

Histology:

Melanocytic nevi consisting of several types of nevi (common melanocytic nevi and dendritic blue nevi).

6.6.1.13  Melanocytic nevus of the conjunctiva

Pictures

Under conjunctival epithelium there are groups of pigmented melanocytes:
Melanocytic nevus, conjunctiva, HE 40x (2427)

6.6.2  Melanoma

Introduction:

Malignant tumor of melanocytes. Several variants exist.

Clinical signs:

  • no special site of predilection, more often on face and back (men) or lower extremities (women)
  • I. superficial spreading melanoma (SSM): most common form: slowly growing brown macule
  • II. lentigo maligna melanoma: develops from lentigo maligna (which is in situ melanoma of elderly people) when invasion appears
  • III. nodular melanoma: red, brown, black tumor, often ulcerating and/or bleeding
  • IV. acral lentiginous melanoma: nails, fingers, palms, soles
  • special clinical variants: melanoma of mucous membrane, conjunctina, amelanotic melanoma
  • ABCD rule: A  —  asymmetry, B  —  border, C  —  colour, D  —  diameter

Pictures

Malignant melanoma:
Melanoma, Macro (3857)

Melanoma, sole:
Melanoma, Macro (3861)
Melanoma, Macro (3863)
Melanoma, Macro (3865)

Nodular melanoma, trunk:
Melanoma, CLINIC (807)

Nodular amelanotic melanoma, trunk:
Melanoma, CLINIC (808)

Nodular melanoma, face:
Melanoma, CLINIC (809)

Nodular melanoma, advanced:
Melanoma, CLINIC (811)

Superficial spreading melanoma, detail:
Melanoma, CLINIC (812)

Superficial spreading melanoma, back:
Melanoma, CLINIC (813)

Superficial spreading melanoma:
Melanoma, CLINIC (814)

Acral lentiginous melanoma, advanced:
Melanoma, CLINIC (815)

Melanoma of the vulva:
Melanoma, CLINIC (816)

Metastatic melanoma, face:
Melanoma, CLINIC (806)

Metastatic melanoma, back:
Melanoma, CLINIC (810)

Metastases of malignant melanoma, peritoneum:
Peritoneal metastasis of a melanoma, Macro, autopsy (5484)

Further examples of melanoma:

6.6.2.1  Lentigo maligna

Clinical signs:

  • usually on the face of elderly people (sun exposed skin)
  • slowly growning macule, irregular borders
  • color varies in one lesion (various shades of brown)
  • later (after years) nodularities — sign of invasion (lentigo maligna melanoma)

Pictures

Lentigo maligna, lower eyelid and angulus oculi:
Lentigo maligna, CLINIC (784)

Lentigo maligna, cheek:
Lentigo maligna, CLINIC (785)

Further examples of lentigo maligna:

Histology:

In situ malignant melanoma (malignant melanocytes scattered in all epidermal layers). Epidermis is atrophic. Prominent dermal solar elastosis and almost always lymphocytic infiltration.

6.6.2.2  Lentigo maligna melanoma

Introduction:

Develops after some years from lentigo maligna, when the invasive growth starts and the tumor spreads into the dermis.

Clinical signs:

  • after years nodular change in lentigo maligna (sign of invasion)

Histology:

Like lentigo maligna, but invasion of the dermis by malignant melanocytes.

Pictures

Lentigo maligna melanoma:
Lentigo maligna melanoma, LMM, HE 100x (5438)

6.6.2.3  Intraepidermal melanoma (melanoma in situ)

Histology:

Melanocytes (some of them atypical) spread in all levels of the epidermis. No dermal invasion. Variable lymphocytic infiltrate and scattered melanophages are often present.

Melanocytes are large, with large nuclei varying in size and shape. Nucleoli are usually present. Mitotic activity is usually present.

Malignant melanocytes may spread into the adnexal epitelium.

If prominent solar degeneration of elastic and epidermal atrophy are present, the lesion should be considered lentigo maligna.

6.6.2.4  Superficial spreading melanoma, SSM

Histology:

Malignant, atypical melanocytes are present in all layers of the epidermis (scatter). Nuclei are irregular, chromatin is clumped, nucleoli are prominent. Some mitotic activity is usually present.

The tumor infiltrates papillary dermis and spreads horizontally: thin, asymmetric melanocytic proliferation, unsharp borders, irregular distribution of melanin.

Dermis shows fibrosis, variable lymphocytic infiltrate and melanophages.

Pictures

Superficial spreading melanoma:
Melanoma, superficial spreading (SSM), HE 40x (2296)
Melanoma, superficial spreading (SSM), HE 40x (2297)

Another case:
Superficial spreading melanoma, HE 60x (6281)

Another case:
Superficial spreading melanoma, HE 40x (4155)

Another case:
Superficial spreading melanoma, HE 40x (2446)
Superficial spreading melanoma, elastic fibres 40x (2445)

Another case:
Superficial spreading melanoma, HE 40x (2330)

Another case:
Superficial spreading melanoma, HE 40x (2331)

Another case:
Intraepidermal melanoma, HE 40x (3586)

Another case:
Superficial spreading melanoma, HE 40x (2741)
Superficial spreading melanoma, Ki67 40x (2742)

Another case:
Melanoma, HE 60x (12914)

Another case, proliferation marker Ki67:
Superficial spreading melanoma, Ki67 40x (2744)

Another case, with small subepidermal vesicles:
Superficial spreading melanoma, HE 20x (3506)
Superficial spreading melanoma, HE 40x (3507)

Small melanoma:
Superficial spreading melanoma, SSM, HE 20x (4807)  [zoomify]
Superficial spreading melanoma, SSM, HMB45 20x (4808)

SSM on (slightly) sun damaged skin:
Superficial spreading melanoma, SSM, HE 20x (5416)

Superficial spreading melanoma:
Superficial spreading melanoma, SSM, HE 60x (10827)

Superficial spreading melanoma:
Superficial spreading melanoma, SSM, HE 60x (10829)

Superficial spreading melanoma:
Superficial spreading melanoma, SSM, HE 60x (12703)

Superficial spreading melanoma:
Superficial spreading melanoma, SSM, HE 60x (12472)

Superficial spreading melanoma:
Superficial spreading melanoma, SSM, HE 60x (12294)

Superficial spreading melanoma:
Superficial spreading melanoma, SSM, HE 40x (13202)

Superficial spreading melanoma:
Superficial spreading melanoma, SSM, HE 60x (12742)

Superficial spreading melanoma:
Superficial spreading melanoma, SSM, HE 40x (10938)

Superficial spreading melanoma, nodularity:
Superficial spreading melanoma, vertical growth, HE 60x (14021)

Melanoma, SSM, with baloon melanocytes:
Balloon cell melanoma, HE 60x (13632)

6.6.2.4.1  Superficial spreading melanoma, vertical growth

Histology:

Develops from superficial spreading melanoma. Melanocytic infiltration reaches deep into the corium and vertical growth starts to prevail. Groups of melanocytes of variable size are formed, contributing to the asymmetry of the lesion. The melanocytes within these groups are usually large, epithelioid, low melanin production, with prominent atypia, nucleoli and mitotic activity.

In time large nodularity reaching into the deep dermis or subcutis is formed. The superficial part of the tumor continues to spread laterally and is wider than the tumor; epidermal scatter is present.

6.6.2.5  Nodular melanoma

Histology:

Large, clearly malignant melanocytic tumor reaching into the deep dermis. Formed by large tumorous nodule with only minimal signs of epidermal invasion and superficial lateral spread.

Prominent melanocytic atypia, usually high mitotic activity. Differential diagnosis against melanoma metastasis may be difficult.

Pictures

Nodular melanoma:
Melanoma, nodular, HE 5x (2526)
Melanoma, HE 10x (2713)
Melanoma, nodular, HE 40x (2525)
Melanoma, HE 40x (2714)

Another case:
Nodular melanoma, HE 20x (2712)

Another case:
Superficial spreading melanoma, HE 20x (3619)
Superficial spreading melanoma, HE 40x (3620)
Superficial spreading melanoma, Ki67 40x (3621)
Superficial spreading melanoma, Melan A 40x (3606)

Another case of ulcerating nodular melanoma:
Nodular melanoma, ulcerated, HE 40x (3633)
Nodular melanoma, ulcerated, S100 20x (3632)
Nodular melanoma, Ki67 20x (3674)

Part of the large nodular melanoma with mitotic activity, production of melanin and cellular and nuclear polymorphism:
Nodular melanoma, large, HE 40x (4186)

Nodular melanoma with no lymphocytic infiltrate, rather symmetric, of regular melanocytes, with slight mitotic activity, without maturation; further metastasis to the axillary lymphnode after three years (male, 26 years, forearm):
Melanoma, nodular, HE 60x (6302)
Melanoma metastasis, axillary lymphnode, HE 60x (6303)

Nodular melanoma, traumatized, high mitotic activity:
Nodular melanoma, HE 60x (6413)
Nodular melanoma, Melan A 40x (6412)

Nodular melanoma:
Nodular melanoma, HE 40x (13198)

Nodular melanoma:
Nodular melanoma, HE 40x (13199)

Nodular melanoma:
Nodular melanoma, HE 60x (6438)

Nodular melanoma:
Nodular melanoma, HE 60x (10828)

Nodular melanoma:
Nodular melanoma, HE 40x (12471)

Nodular melanoma:
Nodular melanoma, HE 60x (14008)

Nodular melanoma:
Nodular melanoma, HE 60x (14009)

Flat nodular melanoma with atypical melanocytes and mitotic activity:
Nodular melanoma, mitoses, atypia, HE 40x (12702)

Nodular melanoma, very high mitotic activity:
Nodular melanoma, high mitotic activity, HE 60x (13739)

Nodular melanoma, spindle melanocytes:
Spindle cell nodular melanoma, HE 60x (13430)
Nodular melanoma, spindle melanocytes, Melan A 20x (13425)

Heavily pigmented melanoma (equinne type?):
Malignant melanoma, equinne type, HE 60x (13674)

Recurrence of nodular melanoma:
Recurrent nodular melanoma, HE 60x (14065)
Recurrent nodular melanoma, HE 60x (14066)

6.6.2.5.1  Nevoid melanoma

Introduction:

Melanoma resembling common melanocytic nevus.

Histology:

One of possible presentation is verrucous lesion in elderly person, resembling verrucous melanocytic nevus.

Sheets of melanocytes, variable atypia, scattered mitoses.

Pictures

Nevoid melanoma:
Nevoid melanoma, HE 60x (14062)

6.6.2.6  Acrolentiginous and mucosal melanoma

Clinical signs:

  • pigmented macule located at acral areas (palms, soles, subungual)
  • similar lesions occur on mucous membranes

Histology:

Intraepidermal part of the tumor consists of large, atypical melanocytes, spread mostly in the basal layers of the epidermis. Focal melanocytic scatter is usually present. Irregular transcutaneous eliminiations of melanin.

The tumor spreads laterally. Gradually dermal nodules consisting of round and spindle shaped melanocytes are formed. Some of melanocytes have dendritic processes.

The melanocytes may spread within the epithelium of eccrine sweat glands. Perineural invasion may be present.

Dermal fibrosis, irregular lymphocytic infiltrate and scattered melanophages complete the picture.

6.6.2.7  Melanoma ex nevo

Introduction:

About 20% of melanomas arise in pre-existing melanocytic nevus (most melamas arise de novo).

Histology:

Melanoma (usually in superficial parts, SSM) and remnants of intradermal part of the preexisting nevus (regular, benign melanocytes).

Pictures

Melanoma ex nevo:
Superficial spreading melanoma ex nevo, HE 40x (2329)

Another case, Ki67 marker is positive in melanoma and negative in the remnants of the nevus:
Melanoma in nevo, HE 40x (2528)
Melanoma in nevo, HE 100x (2527)
Melanoma in nevo, Ki67 40x (2529)

Melanoma ex nevo:
Melanoma in nevo, HE 20x (4811)  [zoomify]

Melanoma, probably ex nevo, SSM with nodularity:
Superficial spreading melanoma ex nevo, HE 20x (4992)  [zoomify]

6.6.2.8  Balloon cell melanoma

Clinical signs:

  • clinical features correspond to common melanomas

Histology:

The melanoma consists of balloon melanocytes (large, with broad cytoplasm), but the architecture, nuclear polymorphism and mitotic activity correspond to common melanomas.

Pictures

Balloon cell melanoma:
Balloon cell melanoma, HE 40x (2295)

6.6.2.9  Small cell melanoma

Clinical signs:

  • clinical features correspond to common melanomas

Histology:

Melanoma is composed of sheets of small round melanocytes.

6.6.2.10  Desmoplastic melanoma

Clinical signs:

  • plaque or nodule
  • about half of the cases are pigmented
  • location: sun exposed areas, namely head, neck (ear, lip, nose)

Histology:

Spindle shaped malignant melanocytes, often unpigmented. Sometimes the cells form fascicles. Atypia of the cells is mild or moderate. The tumor usually reaches deep into the dermis. There is patchy lymphocytic infiltrate within the tumor. Perineural involvement is common.

Immunoprofile: S100 variable, often weak; Melan A usually negative, vimentin positive.

6.6.2.11  Melanoma developing within congenital nevus, child, 6 years

MUDr. Marta Ježová, PhD.

Clinical signs:

  • melanomas are more common in large congenital nevi
  • melanomas in small nevi (under 10 cm) in children are rare
  • clonal (nodular) proliferations are usually benign (espicially in children)

Histology:

General signs of melanomas. The diagnosis can be difficult.

6.6.2.12  Melanoma of the conjunctiva

Pictures

Solid areas of melanocytes, rare mitotic activity:
Conjunctival melanoma, HE 60x (13953)

6.6.2.13  Melanoma metastases

Histology:

Nodule of melanocytes, often multiple, located intradermally, usually roundish. Usually at least some epidermotropism is present (epidermotropic metastases). Mitotic activity and cellular atypia are usually prominent. Melanin production is variable.

Case study:

Metastatic amelanotic malignant melanoma
MUDr. Hana Jedličková, PhD.

Introduction:

Amelanotic melanoma is a rare variant of malignant melanoma. Due to its lack of the pigment, the clinical diagnosis is often difficult. Melanin synthesis is disturbed in increased hypoxia and acidity of malignant cells. Tyrosinase, which is essential for melanin synthesis, is accumulated and degraded within the endoplasmic reticulum. Not only late clinical recognition but also biochemical properties of amelanotic melanoma enhance the metastatic spread of this variant. Amelanotic metastases are not uncommon also in cases of primary pigmented melanomas.

History:

70 year old man noticed eruptive pink papules on his right shin in a vicinity of a scar after the taking of a vein graft. The clinical diagnosis was eruptive xanthoma; the papules were examined histologically with the result of a melanocytic nevus.

The patient had a history of hypertension and chronic heart disease; he had had a coronary artery bypass surgery two years earlier. For some time he had a chronic defect on his right sole which was considered as an ischemic ulceration by his physician.

As the histological results did not correlate with the clinical picture, the patient was examined by a dermatologist and clinical diagnosis of an amelanotic metastatic melanoma of the sole was made, This diagnosis was confirmed by histopathology.

Clinical signs:

Several pink tough papules, 3 – 5mm in diameter, on the anterior aspect of the right shin. An ulcer 2 cm in diameter with irregular borders and small amount of light brown pigment in the adjacent skin was found on the right sole.

Histology:

A symmetric dome shaped papule. The epidermis with a collarette and no epidermotropism. Dermis is filled with an infiltrate of melanocytes with nuclear atypias and prominent nucleoli; atypical mitoses can be found. Superficially the cells are organized in nests, the lower margin is sharply demarcated, and the pigment is sparse. The cells are Ki 67 and Melan A positive.

Pictures

Primary melanoma of the sole:
Metastazing melanoma of the sole, CLINIC (4071)

Metastases of the melanoma on the sole, note the scar where the venous graft for the bypass was taken:
Melanoma metastases (scar after venous graft removal), CLINIC (4070)

Metastases of a melanoma, with maturation, minimal epidermotropism, minimal mitotic activity, symmetry, flat bottom:
Metastasis of a melanoma, HE 40x (3529)
Metastasis of a melanoma, HE 40x (3530)
Metastasis of a melanoma, Melan A 20x (3573)
Metastasis of a melanoma, Ki67 40x (3574)

Melanoma metastasis:
Metastasis of a melanoma, HE 40x (10949)
Metastasis of a melanoma, HE 40x (10950)

Melanoma metastasis:
Metastasis of a melanoma, HE 20x (5466)
Metastasis of a melanoma, HE 20x (4815)  [zoomify]


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