Dermatology Online Journal

Epidermolytic acanthoma of the scrotum: A rare mimicker of condyloma acuminatum
Saivivek R Bogale MD, C Stanley Chan MD, Holly McIntire MD, Sylvia Hsu MD
Dermatology Online Journal 17 (1): 6

Department of Dermatology, Baylor College of Medicine, Houston, Texas. shsu@bcm.edu

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Abstract

Epidermolytic acanthoma is a rare benign tumor that is characterized by epidermolytic hyperkeratosis on histopathology. Epidermolytic acanthoma usually presents in adulthood as an asymptomatic tumor less than 1 cm in diameter with a verrucous surface. Whereas the lesions can present in either an isolated solitary, localized, or disseminated form, there tends to be a predilection for the genitoscrotal area.

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Introduction

Epidermolytic acanthoma (EA) is a rare benign tumor that is characterized by epidermolytic hyperkeratosis on histopathology. It was first described in 1970 by Shapiro and Baraf [1] who reported 6 cases of solitary lesions and 1 case of multiple lesions on the scrotum that clinically resembled condyloma acuminatum. Epidermolytic acanthoma usually presents in adulthood as an asymptomatic tumor less than 1 cm in diameter with a verrucous surface [2]. Whereas the growths can present in either an isolated solitary, localized, or disseminated form, there tends to be a predilection for the genitoscrotal area [3].

Case report

Figure 1
Figure 1. Gray-white papules on the scrotum

A 55-year-old man presented to our clinic for a routine total body skin exam. The patient was an otherwise healthy male with no significant past medical history. He denied any family history of similar lesions. He was in a monogamous heterosexual relationship with the same sexual partner for many years. He denied knowledge of any recent trauma, radiation exposure, or use of any immunosuppressive drugs. On physical examination the patient had multiple 2-4 mm gray-white papules on the scrotum (Figure 1). Some were dome-shaped and others were flat-topped. The lesions were asymptomatic and of no concern to the patient. He believed the lesions may have been present for about a year.

Figure 2	Figure 3
Figure 2. Low-power view of shave biopsy showing papillomatosis and epidermolytic hyperkeratosis (H&E, x40) Figure 3. High-power view of shave biopsy showing epidermolytic hyperkeratosis. There is also evidence of compact hyperkeratosis in the stratum corneum, an increased number of large keratohyaline granules, and perinuclear vacuolization of the cells in the stratum spinosum and in the stratum granulosum. (H&E, x100)

A shave biopsy of a papule revealed hyperkeratosis with suprabasilar keratinocyte vacuolization (Figures 2 and 3) consistent with a diagnosis of epidermolytic acanthoma of the scrotum. The patient did not want any treatment for this condition because the lesions were of no concern to him.

Discussion

Epidermolytic acanthoma is a benign verrucous growth that exhibits epidermolytic hyperkeratosis on histopathology [3]. Epidermolytic hyperkeratosis is characterized by compact hyperkeratosis and vacuolar degeneration of keratinocytes in the spinous and granular layers and encompasses a group of disorders with an abnormality of epidermal maturation [3]. Electron microscopy commonly reveals the preservation of desmosomes with evidence of tonofilament clumping, cytoplasmic vacuolation, and variably sized keratohyalin granules [4, 5]. Epidermolysis is a fundamental histologic finding in epidermolytic acanthoma (EA) and 3 hereditary skin diseases: bullous congenital ichthyosiform erythroderma, systemized verrucous nevus, and hereditary palmoplantar keratoderma of Vörner [3].

Epidermolytic acanthoma is most commonly caused by mutations in keratins 1 and 10 [6]. Cohen [7] used immunohistochemistry techniques to demonstrate a decrease in keratin 1 and keratin 10 expression in lesions of solitary epidermolytic acanthoma as compared to adjacent, histologically normal-appearing skin. Whereas bullous congenital ichthyosiform erythroderma, which shows similar epidermolytic hyperkeratosis, is caused by genetic mutations in keratins 1 and 10, acquired mutations related to exogenous factors are more likely in epidermolytic acanthoma [5].

The precise etiology of EA though is unknown, but various authors have suggested human papillomavirus (HPV), other viral infections, ultraviolet radiation, sunburn, immunosuppression, and trauma as playing a role in the pathogenesis [6]. Although HPV has been implicated as a causative factor in EA, immunohistochemical and molecular studies have failed to detect viral genome in either genital or extragenital lesions [7, 8]. Sun exposure could be involved in the pathogenesis of EA, as multiple epidermolytic acanthomas localized to the back have been reported following severe sunburn [9]. Immunosuppression has also been strongly implicated in the pathogenesis of disseminated epidermolytic acanthoma [10, 11]. Our patient did not have any discernible predisposing factors.

The genital location of this condition and its clinical appearance often leads to confusion with a number of other sexually transmitted diseases. The differential diagnosis in our case initially included small papules of condyloma accuminata and molluscum contagiosum. Clinical and histopathological findings of epidermolytic acanthoma may also sometimes mimic those of HPV infection [12]. It is important to rule out the presence of HPV to prevent misdiagnosis and mistreatment of the lesion as an HPV infection. Epidermolytic acanthoma is also often confused with bowenoid papulosis or seborrheic keratosis [2].

Treatment is not necessary for epidermolytic acanthoma because of its benign nature unless the lesions are particularly distressing to the patient. Solitary epidermolytic acanthoma lesions may be treated by surgical excision [13] or other destructive options, such as cryotherapy [2]. Jang et al [13] also reported a case of multiple epidermolytic acanthomas of the scrotum treated with topical imiquimod, which resulted in almost complete clearance after 4 weeks of treatment.

Our case highlights the importance of correlating clinical examination with histopathological findings in diagnosing a rare condition, such as epidermolytic acanthoma. Although relatively uncommon, it is important to consider epidermolytic acanthoma in the differential diagnosis of asymptomatic verrucous lesions in the genitalia. Epidermolytic acanthoma is often confused with other conditions, such as condylomata acuminata, molluscum contagiosum, and bowenoid papulosis because of its warty appearance [2]. The considerable variability reported in the literature regarding the anatomical locations affected and the number of lesions present suggests that many factors may be involved in the pathogenesis of this disorder.

References

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