A 31-year-old Caucasian man presented to our clinic with a 4-month history of a solitary mass on the left mandibular area believed to be an abscess. It was slightly tender and exuded pus from several openings within the mass. He had a history of being HIV positive for 7 years. His HIV was well controlled on once daily oral Biktarvy containing bictegravir, emtricitabine, tenofovir, and alafenamide, and he had a normal CD4+ count and an undetectable viral load. Clinical examination showed a 5 by 5 cm erythematous mass with a rough surface and a few draining sinuses over the right mandibular area (Figure 1). A previous X-ray showed no evidence of periostitis or bone destruction and he had previously seen a dentist and a dental sinus was ruled out. The differential diagnosis when seen included infectious causes such as actinomycosis, a deep fungus, tuberculosis (TB), and atypical mycobacteria. Two 4-mm punch biopsies were done, one for histology and one for cultures. Skin biopsy showed a squamous-lined cystic structure at the deep biopsy edge compatible with a sinus tract (Figure 2). Periodic acid-Schiff (PAS), Grocott's methenamine silver (GMS), Ziehl-Neelsen (ZN), and Fite stains were all negative. Cultures sent for aerobic and anaerobic cultures grew a few Staphylococcus aureus but were negative for Actinomyces species. Tissue culture for deep fungus, TB, and atypical mycobacteria were all negative. He was treated with oral doxycycline 100 mg PO BID for 2 months, and when reassessed, the morphology of the lesion had markedly changed (Figure 3) to a flesh-colored indurated plaque with marked cribriform scarring. A full skin examination at this time showed no lesions in the axillae, groin, and buttocks except for a 5-mm depressed scar in the left lower abdomen which the patient attributed to an "ingrown hair."
At this time, the clinical appearance suggested HS localized to the face. An incisional biopsy from the plaque including an area of cribriform scarring was submitted for pathology and showed an acute folliculitis with deep dermal fibrosis and a lymphoplasmacytic infiltrate. All repeated cultures were negative. He was put on a course of oral isotretinoin and the plaque was injected with intralesional triamcinolone acetonide 10 mg/cc and he has a good response to this treatment.