Multiple Eruptive Syringomas on the Penis

To the Editor:

Syringomas are small, benign, asymptomatic eccrine or apocrine tumors that present as multiple discrete flesh-colored papules. They are more common in females than males.¹ The etiology of eruptive syringomas is unclear, though an inflammatory process has been implicated in the abnormal proliferation of sweat glands.² However, a minority of tumors have been known to have an autosomal-dominant mode of transmission. Multiple or eruptive syringomas are associated with Down syndrome, Marfan syndrome, Ehlers-Danlos syndrome, and Blau syndrome.³ The clear cell variant has been found to be associated with diabetes mellitus.⁴ Syringomas most commonly appear on the lower eyelids, upper cheeks, neck, and upper chest; presentation on the penis is rare.⁵ We report a case of multiple eruptive syringomas located exclusively on the penis mimicking a sexually transmitted condition.

A 53-year-old man who was otherwise healthy presented with multiple flesh-colored papules on the penis that initially began to develop 30 years prior, but increased crops of lesions appeared 4 to 6 weeks prior to presentation. The patient described the lesions as rashlike, nonpruritic, and sensitive to the touch. He denied any discharge, oozing, crusting, or bleeding from the lesions. He did not report any high-risk sexual behaviors and stated that he was in a monogamous relationship with his wife. He had a medical history of molluscum contagiosum that was diagnosed and treated with cryotherapy 30 years prior; however, he did not have a history of any other sexually transmitted diseases. He also did not have a history of diabetes mellitus or thyroid disease.

Physical examination revealed multiple pink papules on the dorsal and ventral shaft of the penis, measuring 2 to 4 mm in diameter, with koebnerization (Figure 1). Based on clinical examination, the differential included condyloma, inflamed seborrheic keratosis, bowenoid papulosis, atypical molluscum contagiosum, or lichen planus. Consequently, a punch biopsy of the penile shaft was performed and histopathologic examination revealed proliferation of ducts focally that were tadpole shaped and embedded in a sclerotic stroma. The lining of the ducts was composed of cuboidal cells, some with clear cell change. The microscopic findings were consistent with penile syringomas (Figure 2). Laboratory results revealed the patient was negative for human immunodeficiency virus, hepatitis B, hepatitis C, and syphilis. The patient was given topical hydrocortisone butyrate and tacrolimus for symptomatic treatment. He declined further aggressive treatment.

Figure 1. Penile syringoma with multiple pink papules on the dorsal and ventral shaft of the penis, measuring 2 to 4 mm in diameter, with koebnerization. Circle indicates biopsy site.

Figure 2. Penile syringoma. A, Histopathology revealed proliferation of ducts focally that were tadpole shaped and embedded in a sclerotic stroma (H&E, original magnification ×20). B, The lining of the ducts was composed of cuboidal cells and demonstrated clear cell change (H&E, original magnification ×100).

Due to the rarity of syringomas on the penis, presentation of these benign eccrine tumors can be commonly mistaken for lichen planus, molluscum contagiosum, genital warts, or bowenoid papulosis.⁵ The characteristic histopathology of syringomas consists of multiple, small, tadpole or paisley tie–shaped ducts within an eosinophilic stroma. Often, the findings can be histologically confused with desmoplastic trichoepithelioma, morpheaform basal cell carcinoma, and microcystic adnexal carcinoma. Although the histopathology of our patient’s biopsy showed clear cell change, the patient did not report a history of diabetes mellitus, which is a disease that can be associated with the clear cell variant of syringoma. Because syringomas are benign tumors, treatment is not medically necessary unless the lesions are symptomatic. Treatment often is regarded as challenging, as lesions often recur and scarring is a consideration. Possible treatments for removal of the benign papules include surgical excision, electrodesiccation and curettage, shave removal, chemical peels, liquid nitrogen cryotherapy, and CO₂ laser vaporization.⁶

To prevent misdiagnosis and unnecessary treatment, it is important to have syringomas as part of the differential diagnosis when patients present with multiple small flesh-colored papules on the penis. The lesions should be biopsied for accurate diagnosis and to provide reassurance to patients who usually come in for evaluation for fear of having acquired a sexually transmitted disease.