Contents
 

Benign epidermal tumors



6  Skin tumors

6.2  Benign epidermal tumors

6.2.1  Seborrhoic keratosis

Clinical signs:

  • common in elder people, usually multiple
  • hyperkeratotic papules, size from several milimeters to 1 – 2 cm
  • color: various shades of brown
  • papillomatous surface, with greasy, friable scales

Pictures

Seborrhoic keratosis:
Verruca seborrhoica, CLINIC (920)

Seborrhoic keratosis, temple:
Verruca seborrhoica, CLINIC (921)

Multiple seborrhoic keratoses and dyskeratoses, the back:
Verruca seborrhoica, CLINIC (922)

Seborrhoic keratoses:
Verruca seborrhoica, CLINIC (3418)

Verruca seborrhoica, CLINIC (3419)

Verruca seborrhoica, CLINIC (3420)

Further examples of seborrhoic keratoses:

Histology:

Tumor consists of basaloid (= roundish, sligtly paler, regular with relatively large nuclei) keratinocytes). Horn cysts with abrupt keratinization are often present (basaloid cells of the tumor suddenly mature into regular keratin lamellae. These lamellae have no parakeratosis and in HE staining are usually slightly bluish. Another common signs are akanthosis, hyperkeratosis and squamous eddies (especially in irritated form).

Acanthotic form is characterised by thickened epidermis with variable acanthosis; horn cysts are common

Melanoacanthotic form see melanoacanthoma

Reticular form consists of multiple, interconnected epithelial bands, often only two cell layers thick.

Clonal form forms nests of regular, basaloid cells within the epidermis

Hyperkeratotic form characterised by prominent hyperkeratosis.

Irritated type of seborrhoic keratosis is characterised by multiple squammous eddies. These eddies are small, without cellular atypia and are present in large numbers. Inverted follicular keratosis is similar or identical process.

Pictures

Seborrhoic keratosis:
Verruca seborrhoica acanthotic, HE 20x (2031)

Verruca seborrhoica acanthotic, HE 40x (2032)

Clonal seborrhoic keratosis:
Verruca seborrhoica, clonal, HE 40x (2262)

Irritated seborrhoic keratosis:
Verruca seborrhoica, irritated, HE 40x (2749)

Another case of irritated seborrhoic keratosis:
Verruca seborrhoica, irritated, HE 40x (5033)

Melanoacanthotic, pigmented seborrhoic keratosis:
Verruca seborrhoica, pigmented, HE 40x (2750)

Reticular type of seborrhoic keratosis:
Verruca seborrhoica, reticulated, HE 40x (2751)

Reticular type of seborrhoic keratosis, another case:
Verruca seborrhoica, reticulated, HE 40x (3624)

Papillomatous seborrhoic keratosis:
Verruca seborrhoica, papillary, HE 20x (5429)

Seborrhoic keratosis, clonal, pigmented:
Seborrhoic keratosis, clonal, pigmented, HE 60x (13272)

6.2.1.1  Melanoacanthoma

Clinical signs:

  • location: head, neck, trunk
  • age: elderly people
  • dark pigmented papule, solitary, size up to 3 cm

Histology:

Deeply pigmented variant of the seborrhoic keratosis, consisting of a mixture of keratinocytes (some ot them basaloid) and dendritic melanocytes.

6.2.1.2  Dermatosis papulosa nigra

Clinical signs:

  • small pigmented papules
  • location: face, neck, trunk
  • affects black adults

Histology:

Shallow acanthosis with interconnecting rete ridges, pronounced hyperpigmentation of the basal layer, keratinous cysts and invaginations. Similar to reticulate seborrhoic keratosis, but is not formed by basaloid (small, round) cells.

6.2.2  Lentigo solaris

Clinical signs:

  • multiple brown pigmented macules, size up to more than 1 cm
  • age: elderly people
  • location: insolated areas

Histology:

Small, bud-like acanthotic proliferations; hyperpigmentation of the basal layer; variable increase of melanocytes; solar elastosis.

6.2.2.1  PUVA lentigo

Etiology:

PUVA therapy (oral methoxsalen photochemotherapy) in (psoriatic) patients.

Clinical signs:

  • patients treated by PUVA (psoriasis and dome other diseases)
  • appears after long lasting therapy
  • maculae usually regress after the therapy is discontinued
  • location: sun protected areas of the body (buttocks)
  • brown maculae of variable size

Histology:

Melanophages in the upper corium, slight acanthosis, increased number of melanocytes.

6.2.3  Melanosis of Becker (Becker's nevus)

Clinical signs:

  • large pigmented patch
  • smooth surface, often hairy
  • age: apperas during the puberty, lasts undefinetly
  • location: trunk (shoulders)

Histology:

Regular acanthosis, hyperpigmented epidermis, sometimes increased amount of hair follicles.

Pictures

Melanosis Becker:
Melanosis of Becker, HE 40x (2610)

6.2.4  Stucco keratosis

Clinical signs:

  • small, hyperkeratotic papules
  • symmetric
  • location: usually distal parts of the extremities, ankles

Histology:

Small papillomatous lesions with some hyperkeratosis and no parakeratosis (resembles small seborrheic keratosis).

6.2.5  Acrokeratosis verruciformis Hopf

Clinical signs:

  • multiple flat hyperkeratotic papules
  • autosomal dominant transmission
  • location: distal part of the extremities (dorsa of the hands, feet, forearms)

Histology:

Hyperkeratosis, no parakeratosis, papillomatosis (thin papillae), slight acanthosis.

6.2.6  Hyperkeratosis lenticularis perstans of Flegel

Clinical signs:

  • hyperkeratotic papules
  • location: feet, lower legs
  • some cases have autosomal dominant mode of inheritance

Histology:

Hyperkeratosis, no parakeratosis, papillomatosis and acanthosis on the periphery, central thinning of the epidermis. Often dense lymphocytic infiltrate is present within the dermis.

6.2.7  Confluent and reticulated papillomatosis

Clinical signs:

  • location: usually sternum
  • centrally confluent, on the margin reticular papillomatosis similar to acanthosis nigricans

Histology:

Slight hyperkeratosis, papillomatosis, often colonization with Pityrosporon (Malassezia) orbiculare.

6.2.8  Acanthosis nigricans

Introduction:

Several diagnostic units: acanthosis nigricans benigna (pseudoacanthosis) and acanthosis nigricans maligna

Etiology:

Benign acanthosis nigricans (intertriginous areas); malignant acanthosis nigricans is a paraneoplastic process.

Clinical signs:

  • intertriginous areas
  • papillomatosis
  • hyperkeratosis
  • color: brown
  • the lesions are arranged into crests
  • dull, velvety surface
  • differential diagnosis: erythrasma

Pictures

Acanthosis nigricans, axilla, combined with multiple soft fibromas (the patient after thyroidectomy)
Acanthosis nigricans, CLINIC (641)

Acanthosis nigricans, axilla
Acanthosis nigricans, CLINIC (642)

Acanthosis nigricans maligna, widespread perioral and periorbital lesions
Acanthosis nigricans, CLINIC (643)

Acanthosis nigricans
Acanthosis nigricans, CLINIC (2755)

Acanthosis nigricans, CLINIC (2754)

Acanthosis nigricans, CLINIC (2756)

Acanthosis nigricans, CLINIC (2757)

Histology:

Fine, low papilomatosis, slight orthokeratotic hyperkeratosis (parakeratosis is minimal or none). Keratinocytes are round, sometimes eosinophilic. In some cases increased pigmentation of the basal layer.

6.2.9  Keratotic processes

Introduction:

Processes characterized by multiple, usually tiny hyperkeratotic lesions.

6.2.9.1  Multiple minute digitate keratoses

Histology:

Minute keratoses (size less than 3 mm), no parakeratosis, no relation to the follicles.

6.2.9.2  Postirradiation hyperkeratoses

Histology:

Tiny keratoses (size less than 3 mm), parakeratosis.

6.2.9.3  Minute aggregate keratoses

Histology:

Tiny keratoses and crateriform lesions, no parakeratosis, no relation to the follicles.

6.2.9.4  Waxy dermatosis

Histology:

Papular keratotic lesions with slight papillomatosis and acanthosis.

6.2.10  Warty dyskeratoma (solitary Darier's disease)

Clinical signs:

Solitary papule or small verruca.

Histology:

Papular or verrucous lesion. Irregular acanthosis with acantholysis and dyskeratosis.

6.2.11  Acantholytic acanthoma

Clinical signs:

  • usually solitary lesion
  • papule or nodule

Histology:

Prominent acantholysis (resembles m. Hailey-Hailey or pemphigus), but the process is localized; orthokeratotic.

6.2.12  Verrucous affections caused by papillomavirus (HPV)

6.2.12.1  Verruca vulgaris

Clinical signs:

  • location: variable, often fingers, toes, face
  • solitary and multiple hyperkeratotic papules with warty surface
  • recurrences common, sometimes spontaneous clearing

Histology:

Papillomatous tumor with acanthosis, hyperkeratosis, parakeratosis; thickened, coarse granular layer, vacuolized keratinocytes with basophilic, irregular nuclei (koilocytosis). Parakeratosis is present mostly in the tips of the papillae (christmas tree parakeratosis).

Case study:

Verruca vulgaris forming cornu cutaneum
Pavla Kišová

Clinical signs:

  • female,76 years
  • actinic keratoses, treated by cryotherapy
  • seborrhoic keratoses on the trunk and thighs
  • solar lentigo of the trunk
  • cornu cutaneum of the thigh

Therapy:

Abrasion of the lesion of the thigh.

Pictures

Verruca vulgaris, macro- and microscopic picture (abrasion):
Verruca vulgaris, CLINIC (6266)

Verruca vulgaris, fragments, HE 60x (6265)

6.2.12.2  Verruca filiformis

Clinical signs:

Variant of a vulgar verruca, located usually on the neck.

Pictures

Filiform verrucae, face:
Verruca vulgaris, CLINIC (943)

Histology:

Small, thin lesion with hyperkeratosis and parakeratosis.

Pictures

Verruca filliformis:
Verruca vulgaris, filiform, HE 40x (2335)

6.2.12.3  Verruca plantaris

Clinical signs:

  • embedded papules of the soles, palms, tips and lateral aspects of the fingers
  • painful (tender on pressure)
  • covered with prominent hyperkeratosis

Histology:

Embeded hyperkeratotic papule, papillary arranged, often with coarse, eosinophilic intracytoplasmatic inclusions (may resemble bodies of mulluscum contagiosum). Moreover, intranuclear eosinophilic inclusions are present as well.

Pictures

Verruca plantaris:
Verruca plantaris, HE 20x (2000)

6.2.12.4  Verruca plana

Clinical signs:

  • slightly elevated, flat, smooth papules
  • location: face, dorsa of the hands

Histology:

Slight hyperkeratosis, acanthosis; no papillomatosis and no parakeratosis; cytopathic effect is prominent (many vacuolized keratinocytes).

6.2.12.5  Epidermodysplasia verruciformis

Clinical signs:

  • widespread, tiny, flat papules
  • irregular macules of red-brown color
  • the disease is sometimes familial
  • children are affected more frequently
  • danger of malignant transformation into Bowen's carcinoma or even into invasive squamous carcinoma

Etiology:

Histology:

Slight hyperkeratosis, acanthosis; sometimes with papillomatosis; prominent cytopathic effect: many vacuolated keratinocytes, keratohyaline granules, keratinocytes with broad, slightly basophilic cytoplasm; dyskeratotic cells.

6.2.12.6  Condyloma accuminatum

Clinical signs:

  • location: genital and perianal regions
  • pink, pointed outgrowths (condylomas)
  • larger, cawliflower-like lesions
  • madidation and bad smell in secondary infection

Histology:

Epidermal hyperplasia, acanthosis, parakeratosis; koilocytosis: kerationocytes with perinuclear halo and irregular nucleus (cytopathic effect); papillomavirus can be detected in situ by methods of mollecular pathology.

6.2.12.6.1  Focal epithelial hyperplasia Heck, multifocal papillomavirus epithelial hyperplasia (MPVEH)

Clinical signs:

  • rare disease (native population of America)
  • localization: oral mucosa (lips, buccal mucosa, tongue)
  • multipla pale papules or nodules
  • painless
  • infectious

Etiology:

HPV 13 a 32.

6.2.12.6.2  Hirsutes papillares

Clinical signs:

  • vestibular papillomatosis of the vulva
  • anatomic variant
  • found in approximately 1% of population
  • does not have any relation to viral infection
  • small papillary projections in vulvar introitus, several milimeters in size
  • no therapy is repuired

Pictures

Hirsutes papillares:
Hirsutes papillares, CLINIC (5658)

6.2.12.7  Bowenoid papulosis of the genitalia

Clinical signs:

  • small, multiple, inconspicuous papules, sometimes verrucous
  • location: genitalia
  • tendency towards spontaneous healing, some lesiona may persist and rarely transform into squamous cell carcinoma

Histology:

Dysplastic, bowenoid epithelium (nuclear pleomorphism, crowding, loss of epidermal stratification, mitotic activity); clinical appearance is inconspicuous.

Pictures

Bowenoid papulosis:
Bowenoid papulosis, HE 10x (1214)

Bowenoid papulosis of the penis (male, 26 y):
Bowenoid papulosis of the penis (male 24 y), HE 40x (3687)

Another case of bowenoid papulosis:
Bowenoid papulosis, HE 20x (4430)

Another case of bowenoid papulosis:
Bowenoid papulosis, HE 20x (4431)

Another case of bowenoid papulosis:
Bowenoid papulosis, HE 20x (4433)

Another case of bowenoid papulosis:
Bowenoid papulosis, HE 20x (4434)

Jiný případ bowenoidní papulózy:
Bowenoid papulosis, HE 60x (12978)

Bowenoid papulosis of the penis:
Bowenoid papulosis, HE 100x (5128)

6.2.13  Inverted follicular keratosis

Clinical signs:

  • verrucous lesion without predilections
  • considered to be a variant of a seborrhoic keratosis (irritated type) or a form of vulgar verruca of a separate process.

Histology:

Acanthotic proliferation of benign appearance with multiple, tiny squamous eddies.

6.2.14  Molluscum contagiosum

Etiology:

  • caused by poxvirus

Clinical signs:

  • age: any age, often childred; widespread in immunocompromised patients (esp. AIDS)
  • small papules, often with necrotic center
  • spontaneous resolution

Histology:

Small, acanthotic lesion (often fan shaped acanthosis); superficial areas often desintegrate; the keratinocytes contain large, prominent, basophilic intracytoplasmic inclusions.

6.2.15  Arsenical keratosis

Clinical signs:

  • location: palms, soles, trunk, face
  • gray, hard, hyperkeratotic papules
  • sometimes transition into squamous cell carcinoma or basalioma

Pictures

Multiple arsenical keratoses and basaliomas
Arsen keratosis, CLINIC (965)

6.2.16  Large cell acanthoma

Clinical signs:

  • usually solitary, slightly hyperkeratotic sesion with sharp borders
  • size up to 1 cm

Histology:

Slight hyperkeratosis, keratinocytes are two times as large as in normal epidermis.

Pictures

Large cell acanthoma:
Large cell acanthoma, HE 40x (6143)

6.2.17  Epidermolytic acanthoma

Clinical signs:

  • localized lesion of epidermolytic hyperkeratosis (or disseminated process)

Histology:

The histology corresponds to the epidermolytic hyperkeratosis.

Pictures

Short focus of epidermolytic hyperkeratosis (margin of the epidermolytic acanthoma):
Acanthoma, epidermolytic, HE 20x (4664)

6.2.18  Knuckle pads

Clinical signs:

  • location: dorsal aspect of the joints of the fingers
  • hyperkeratosis

Histology:

Acanthosis, prominent hyperkeratosis.

Pictures

Knuckle pads:
Knuckle pads, HE 40x (1369)

6.2.19  Keratoacanthoma

Clinical signs:

  • location: usually face or dorsa of the hands
  • solitary lesion, rarely multiple
  • firm papule, central crater filled with keration
  • fast growth, spontaneous regression possible

Histology:

Hyperkeratotic papule, formed by central keratinous plug surrounded by proliferating, atypical epidermal invagination. Dysplastic epidermis shows changes corresponding to the well differentiated squamous carcinoma, but cytoplasm is usually more eosinophilic. Mitotic activity is usually high, especially in early lesions. Epithel shows focal necroses and neutrophilic or eosinophilic microabscesses. At the base of the lesion there is usually dense lymphocytic infiltrate, often with admixture of eosinophils. At periphery the tumor shows limited infiltrating behavior.

6.2.20  Pale cell acanthoma

Clinical signs:

  • usually solitary lesion
  • location: lower extremities
  • nodules and plaques, size up to 2 cm, covered with a crust

Histology:

Slight spongiosis, pale, PAS positive keratinocytes (normal basal layer), acanthosis, parakeratosis, neutrophils within the epidermis, sometimes neutrophilic microabscesses, dilated capillaries.

6.2.21  Pale cell papulosis

Clinical signs:

  • multiple white papules
  • location: chest, abdomen
  • very rare disease

Histology:

Pale, PAS positive, alcian blue and mucicarmin positive cells containg mucus are scattered in the basal layer, sometimes higher.

6.2.22  Pseudoepitheliomatous hyperplasia

Clinical signs:

  • reactive process around chronic inflammatory processes, ulceration or tumor
  • may resemble squamous cell carcinoma (clinically and histologically)

Histology:

Irregular acanthosis of somewhat pale epithelium (infundibular); variable inflammatory infiltrate, some chronic process nearby.

Pictures

Pseudoepitheliomatous hyperplasia:
Pseudoepitheliomatous hyperplasia, HE 20x (2002)

6.2.23  Follicular induction

Introduction:

Follicular (trichoepithelial) induction affects basal layers of the epidermis and may resemble bazalioma. It sometimes occures over dermatofibromas, in epidermal nevi and other tumors.

Histology:

The epidermis is thickened, the basal layer is prominent, keratinocytes are basophilic, palisading. Differential diagnosis against superficial bazalioma is sometimes difficult.

6.2.23.1  Sebaceous induction

Analogical process to the follicular induction; rare. Sebaceous glands and acanthosis may apperar over a dermal tumor (especially dermatofibroma).



Top of this page



If you have problems running this atlas (eg. the windows with images do not open), you might have been referenced directly inside the atlas from some other web site. Thus you might have skipped some entry detection routines. Please try entering through the main web page of this atlas at: www.muni.cz/atlases