Erythematous-violaceous plaque in the frontal región

Abstract

A 47-year-old male patient from Peru, a gardener by trade with no significant personal or family medical history, presented with an asymptomatic dermatosis on the forehead that had been evolving for two years. Physical examination of the forehead revealed erythematous-violaceous papules coalescing into a plaque with ill-defined, irregular borders; coalescent nodules partially involved the frontal hairline (Photo 1). The patient denied any history of local trauma, medication use, or infectious diseases in the months preceding the onset of the condition. Differential diagnoses considered included subcutaneous mycosis, papular mucinosis, sporotrichosis, phymatous rosacea, atypical mycobacterial infection, and folliculotropic mycosis fungoides. A 4 mm punch biopsy was performed for histopathological analysis, revealing an unremarkable epidermis. In the dermis, mild vascular dilation was observed, associated with an increased angiocentric chronic lymphocytic inflammatory infiltrate and abundant plasma cells; consequently, a Warthin-Starry stain was performed, yielding a negative result. No granulomatous reaction or deposits of amyloid or mucoid material were evident. PAS and Grocott stains were also negative (Photo 2). Additionally, mycological and bacteriological skin studies were requested—including cultures for atypical mycobacteria and common pathogens—but showed no microbial growth. General laboratory tests and serology (HBV, HCV, HIV) were also performed, with results falling within normal ranges. Due to issues regarding treatment accessibility, second-line therapy was initiated using minocycline (100 mg/day) and 1% ivermectin cream, alongside skin care measures, photoprotection, and avoidance of triggering factors. The patient showed clinical improvement and is currently being followed by our department, with no signs of recurrence or new lesions (Photo 3).