COW-2021-43

CASE OF THE WEEK

2021-43/October 25
Contributors: Maiara Ferreira de Souza and Daniel Athanazio

A man in his early 30s sought urologic care due to a solitary warty lesion in his scrotum. There were no similar skin lesions elsewhere.

Quiz

1. What is the correct diagnosis?

a) Solitary epidermolytic hyperkeratosis (epidermolytic acanthoma)

b) Condyloma acuminatum

c) Epidermodysplasia verruciformis

d) Warty PeIN

e) Molluscum contagiosum

Solitary epidermolytic hyperkeratosis (epidermolytic acanthoma)

Epidermolytic hyperkeratosis is a pattern of skin reaction characterized by hyperkeratosis with granular and vacuolar degeneration of the keratinocytes from the spinous and granular layers. Intracytoplasmic and perinuclear eosinophilic homogenizations are easily observed and correspond to tonofilaments on electron microscopy. The keratohyaline granules appear coarse and basophilic with clumping.

Epidermolytic hyperkeratosis may be observed in a broad spectrum of clinical settings:
– Generalized: Epidermolytic ichthyosis (bullous ichthyosiform erythroderma)
– Systematized or linear: epidermal nevus variant (Ichthyosis hystrix type)
– Palmoplantar: palmoplantar keratoderma variant (Vorner type)
– Solitary: epidermolytic acanthoma
– Multiple discrete: disseminated epidermolytic acanthoma
– Solar keratosis related: a rare variant of solar keratosis
– Follicular: nevoid follicular epidermolytic hyperkeratosis
– Mucosal: epidermolytic leukoplakia

This same pattern can be an incidental finding in common skin lesions such as seborrheic keratoses, melanocytic nevi, squamous cell carcinoma, and melanoma. It may also be seen in epidermal cysts and in normal sun-damaged skin.

Epidermolytic hyperkeratosis may morphologically mimic verruca plana. Verruca plana typically shows basket-woven stratum corneum and round, basophilic nuclei at the centers of the vacuolated cells, without associated irregular keratohyalin granules or clumped keratin filaments.

Epidermolytic acanthoma is an uncommon lesion that presents clinically as a wart in patients of all ages. Caucasian and Japanese are predominantly affected. These discrete lesions may be multiple in a rare, disseminated form. Solitary epidermolytic acanthomas occur most commonly in the genital skin and may be multiple in the scrotum. Trauma and chronic scratching have been implicated. They are usually cup-shaped with papillomatous or flat base, and less frequently flat, papillomatous or polypoid. Such lesions may impose the differential diagnosis with HPV-related lesions, however, lesions with epidermolytic hyperkeratosis pattern are consistently negative for HPV. In the present case, in situ hybridization was negative for HPV.

Calonje E, Brenn T, Lazar AJ, Billings SD. McKee´s Pathology of the Skin. 5th Edition – Elsevier. 2020.

Kazlouskaya V, Lambe J, Elston D. Solitary epidermolytic acanthoma. J Cutan Pathol. 2013 Aug;40(8):701-7.

Patterson JW. Weedon’s Skin Pathology – 5th Edition – Elsevier. 2021. Pg, 24.

Roy SF, Ghazawi FM, Choate KA, McNiff JM. Solitary and multiple epidermolytic acanthoma: A demographic and clinical study of 131 cases. J Cutan Pathol. 2019 May;46(5):305-309

Maiara Ferreira de Souza
Imagepat, Laboratory of Pathology
Salvador, Bahia, Brazil

Daniel Athanazio
Federal University of Bahia
Imagepat, Laboratory of Pathology
Salvador, Bahia, Brazil

Scrotum

Scrotum; Epidermolytic acanthoma; Epidermolytic hyperkeratosis