The hyperpigmented puzzle on the penile shaft: A case of bowenoid papulosis

Dear Editor,

Bowenoid papulosis (BP) is a rare sexually transmitted condition caused by high-risk human papillomavirus notably subtypes 16 and 18.[1] It usually presents as asymptomatic papules with intra-epithelial neoplasia. Although typically benign, early diagnosis and management of BP are crucial due to a potential risk of progression to invasive squamous cell carcinoma if left untreated.[1]

A 37-year-old sexually active male presented with multiple asymptomatic pigmented eruptions on the penile shaft from 8 months. He had high-risk sexual behavior but denied any genital or systemic symptoms with an unremarkable medical history. Clinical examination revealed 2–5 mm, multiple well-defined, discrete, nontender, dark brown-black slightly verrucous papules along the penile shaft [Figure 1a]. No lymphadenopathy, mucosal involvement, or similar lesions anywhere else were noted. Differential diagnoses were genital warts, dermatosis papulosa nigra, seborrheic keratosis, pigmented basal cell carcinoma, and squamous intra-epithelial neoplasia, given the chronicity and hyperpigmentation.

Figure 1.

(a) Clinical image showing multiple, discrete, well-defined, brownish papules over penile shaft (pretreatment), (b) Clinical image showing resolution of bowenoid papulosis lesions after 8 weeks (posttreatment)

He had previously been treated with topical trichloroacetic acid and podophyllotoxin suspected of plane genital warts, but no significant improvement was observed. Later on, dermoscopy and skin punch biopsy were planned. Dermoscopy showed diffuse brown-gray globules over brownish homogenous structureless areas without a specific vascular pattern [Figure 2a and b]. Histopathological examination revealed atypical squamous epithelial cells exhibiting koilocytic changes, disorganization of the epidermal architecture, and associated dermal edema with a sparse lympho-histiocytic inflammatory infiltrate [Figure 3]. The basement membrane was intact, and no mitotic figures were observed.

Figure 2.

(a and b) Dermoscopic picture of bowenoid papulosis depicting diffuse brownish-gray globules in a linear manner (white arrows) over a flat brown background (red asterisk) (DermLite 4, polarized and nonpolarized mode, ×10)

Figure 3.

Photomicrograph showing complete epidermal atypia, atypical squamous cells with koilocytic changes (red arrows), normal basement membrane, dermal edema, and lymphohistiocytic infiltrate in the upper dermis (black arrows) (H and E, ×100, ×200)

Thereafter diagnosis of Bowenoid Papulosis(BP) was established, and treatment was initiated with topical 5% 5-fluorouracil (5-FU) cream, applied twice daily for eight weeks. Significant resolution was observed during subsequent follow-up assessments [Figure 1b].

The clinical presentation of BP is highly variable, from asymptomatic discrete well-defined red-brownish papules with flat, papillomatous, or verrucous surfaces to confluent larger plaques, maybe in annular or linear exhibition.[1] The usual sites of involvement in males are penile shaft, glans, and pubic region while labia, clitoris, and perianal areas in women. Rarely, BP can have extragenital presentation over the face, fingers, or neck, sometimes without any genital involvement.[2] Clinical presentation could mimic genital warts, lichen planus, seborrheic keratosis, melanocytic nevus, warty dyskeratoma, and cutaneous squamous cell carcinoma.

Dermoscopy can serve as an invaluable tool with features such as linear pigmented dots or globules over a homogenous flat brown background without exophytic growths as seen in this case also, supporting BP.[3] It can also have glomerular and dotted vessels.[3] On histopathology, parakeratosis, acanthosis, epidermal atypia, dyskeratotic cells, koilocytes, dilated capillaries, and perivascular diffuse infiltration of lymphocytes are typically seen.[4] Milder histopathological atypia distinguishes it from Bowen’s disease.

Management options include carbon dioxide laser therapy, cryotherapy, electrocoagulation, photodynamic therapy, excisional surgery, and topical applications of 5-fluorouracil (5-FU) or imiquimod cream.[1] Topical 5-FU, as used in our case, is effective due to its antimetabolite action, targeting rapidly dividing atypical cells with minimal scarring.

A high index of suspicion aided by dermoscopy and histopathology is crucial for dermato-venereologists to timely diagnose BP in at-risk individuals presenting with chronic keratotic genital papules.

Declaration of patient consent

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

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.