Asymptomatic Papules on the Scrotum in a Middle-Aged Male

A man in his 50s presented with multiple asymptomatic white- to gray-colored raised lesions of gradual onset on the scrotum since 1 month [Figure 1a]. He was under treatment for genitocrural intertrigo with topical tacrolimus and oral antihistamines for the past 3 years. He did not give a history of high-risk sexual behavior, similar complaints in his partner, or comorbidities. Examination revealed multiple discrete skin-colored papules with a slightly rough surface on the scrotum. There were no abnormalities detected in other body parts. Dermoscopy revealed structureless and polyglobular white areas with lacunae and surrounding hyperpigmentation [Figure 1b]. A 3-mm punch biopsy was taken from one of the lesions. What is your diagnosis?

Figure 1.

(a) Multiple discrete grayish papules on the scrotum (b) Polarized dermoscopy revealed a structureless white area with surrounding subtle hyperpigmentation (Dermlite 4, 10X) (c) Photomicrograph (H and E, 10x) reveal hyperkeratosis, digitations, and irregular vacuolization of the major part of the epidermis with irregular keratohyaline granules

What is the diagnosis?

Answer

Epidermolytic acanthoma

Discussion

A punch biopsy revealed hyperkeratosis with mild digitations, acanthosis, irregular vacuolization of cells of the stratum granulosum, and spinosum along with coarse eosinophilic clumps, reticular degeneration of keratinocytes, and variably aggregated keratohyaline granules [Figure 1c]. No significant abnormalities were noted in the dermis. These features were suggestive of epidermolytic acanthoma. Viral markers including HIV-ELISA were negative. After six and a half months, the patient’s recurrence was successfully treated with electro-section.

Epidermolytic acanthoma (EA) is rare, usually asymptomatic, skin-colored, white or brown papules of variable duration occurring in middle-aged patients.[1,2] They occur on the scrotum, vulva, trunk, extremities, or oral mucosa. Solitary and multiple forms have been described. Multiple lesions are commoner in males, and around the genitals.[1,3] As regards, etiopathogenesis, ultraviolet radiation, and trauma may cause alteration and reduced expression of keratins 1 and 10. In our patient, repeated trauma (scratching) as a consequence of intertrigo have been causal. Human papillomavirus has not been demonstrated in EA lesions.[2]

Dermoscopically, pearly white areas (corresponding to hyperkeratosis), cerebriform pattern, irregular grooves, and peripheral pigmented radial streaks have been previously described.[4] The histological hallmark is epidermolytic hyperkeratosis. Keratinocytes in the granular and spinous layers display reticular degeneration, perinuclear vacuolation with eosinophilic inclusions, and coarse keratohyalin granules.[1,2] Cup-shaped, papillomatous, polypoidal, and acanthotic variants are described.[2] Electron microscopy demonstrates abnormally aggregated perinuclear tonofilaments, organelle degeneration, cytoplasmic vacuolization, and irregular keratohyaline granules.[2] Immunohistochemically, low Ki-67 labeling, weak-absent p21 staining (highlighting minimal proliferation), and absence of human papillomavirus is noted.[1]

Salient differentials comprise verruca vulgaris/condyloma acuminata (CA), bowenoid papulosis, seborrheic keratosis, molluscum contagiosum, verruciform xanthoma, papular acantholytic dyskeratosis, and squamous cell carcinoma.[5]

Differentiating points from CA include lesion size (smaller in EA, larger/cauliflower like in CA), color (light color in EA vs. dark brown in CA), discrete lesions in EA versus agminate/linear lesions (pseudokoebnerization) in CA, and location (on the scrotum/labia majora in EA vs. glans penis, penile shaft/root, groin, pubic area, and perianal area in CA).[1] Dermoscopically, the absence of brown/black dots and hairpin vessels point away from verrucae. Microscopically, koilocytes have pyknotic nuclei surrounded by a well-defined clear halo and are chiefly in the upper epidermal layers.[5] Epidermolytic keratinocytes are noted throughout the stratum malpighii, do not have a well-defined perinuclear lacuna, and possess coarse keratohyaline granules.[3,5] Eosinophilic perinuclear material representing altered keratin is absent in verrucae.[3] Bowenoid papulosis can be excluded on histopathology, which reveals cytologic atypia, unlike EA. Seborrheic keratosis manifests as cerebriform plaques clinically and dermoscopically with milia-like cysts and comedo-like openings. Histopathologic characteristics are pseudohorn cysts and the absence of epidermolytic hyperkeratosis.

Molluscum contagiosum presents with pearly white umbilicated papules in sexually active patients. Whitish round/polyglobular structures are seen in dermoscopy with crown and/or radial vascular patterns. Henderson-Peterson bodies on the Tzanck smear and histopathology are pathognomonic.

Verruciform xanthoma rarely presents on the genitals, but is morphologically similar to EA. Dermoscopic features of glomerular or hairpin vessels with a yellow hue and a papillomatous silhouette with parakeratosis, especially in the crypts, neutrophils, and lymphocytes in the epidermis and foamy macrophages in the dermal papillae are characteristic histologically.

Genital squamous cell carcinoma presents as a hard verrucous plaques with ulceration at times. Histopathologic features of atypical proliferation of squamous cells in the form of nests, and individual cells invading the dermis are characteristic, distinguishing it from the above-mentioned entities.

EA is benign; hence treatment is not mandatory.[1] Treatment modalities comprise retinoids, calcipotriol, imiquimod, tacrolimus/pimecrolimus, electrosurgery, excision, curettage, cryotherapy, and ablative lasers. Although follow-up series are rare, recurrence rates are unknown. In one patient treated with cryotherapy, no recurrence was noted after 6 months.[6] Awareness of EA is important to differentiate this innocuous condition from other similar entities, which carry obvious therapeutic and prognostic implications.

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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.