Case report

A 70-year-old male presented to our clinic with a large ulcerative vegetative perianal mass characterized by bleeding and pain that had been progressing over 3 years. His prior medical history was only notable for a 5 year history of IPinfrequently treated with topical steroids. For the mass, the patient had been previously evaluated by several specialties at outside facilities, including dermatology, infectious diseases, general surgery, and gastroenterology. Prior workup included 2 skin biopsieswhich demonstrated dense mixed inflammation and pseudocarcinomatous hyperplasia (PEH), raising suspicion for an underlying infection. However, an extensive infectious workup including special stains, serology, and wound cultures ruled out atypical fungal infections, hepatitis B and C, chlamydia, herpes simplex virus, syphilis, HPV, and human immunodeficiency virus (HIV). A superficial MRSA infection was treated with antibiotics. Colonoscopy was unremarkable. Previous treatments, including topical and oral antibiotics, triamcinolone, topical lidocaine, and benzoyl peroxide, had failed to provide adequate improvement.

Our initial exam revealed a large, well-demarcated erythematous plaque on the left buttocks with a superimposed 5.5 cm × 4.5 cm ulcerated, friable, cauliflower-like mass that extended into the intergluteal cleft (Fig 1, A). Additionally, 2 erythematous, punched-out ulcers with vesicles were present on the glans penis. A 6-mm punch biopsy was taken from the papillomatous border adjacent to the centrally ulcerating mass as seen in (Fig 1, B), which revealed extensive atypical squamous proliferation within the dermis, consistent with squamous cell carcinoma (Fig 2, A-C). Overlying epidermal changes, including regular psoriasiform acanthosis with neutrophils in the stratum corneum, supported the underlying diagnosis of IP (Fig 2, C). Following further diagnostic evaluation and histopathologic confirmation of SCC, the patient was found to have involvement of both the internal and external anal sphincters and was subsequently treated with surgical resection in combination with chemoradiation.

Fig 1: A, Located on the left medial buttock and extending into the intergluteal cleft is a 5.5 cm × 4.5 cm ulcerated, friable, cauliflower-like mass superimposed on a well-demarcated erythematous scaly plaque. B, A 6-mm punch biopsy was taken from the non-ulcerated border (black circle) of the papillomatous perianal mass.

Fig 2: A, Punch biopsy demonstrating a dermal proliferation of irregular aggregates of atypical keratinocytes with overlying psoriasiform epidermal hyperplasia (2×). B, There are irregular aggregates of atypical keratinocytes admixed with dense mixed inflammation (40×). C, There is regular psoriasiform acanthosis with foci of neutrophils within the stratum corneum. There is underlying lichenoid inflammation (80×).