Dermatopathic lymphadenopathy without cutaneous manifestations presenting as fever of unknown origin: A rare case report

Dermatopathic lymphadenopathy (DL) is a reactive lymphadenopathy typically associated with chronic dermatoses. However, DL presenting with isolated fever and no cutaneous manifestations is exceptionally rare and diagnostically challenging. We report a 73-year-old male with a history of hepatitis B virus-related cirrhosis, diabetes mellitus, and prior eczema who presented with recurrent high-grade fever (39-39.5 ℃) unresponsive to empiric antibiotics and antifungals. Extensive workup, including negative infectious and autoimmune serologies, elevated inflammatory markers (ESR 73 mm/h, CRP 42.4 mg/L), and positron emission tomography/computed tomography (PET-CT) findings of hypermetabolic lymphadenopathy, initially obscured the diagnosis. The diagnosis was ultimately confirmed by lymph node biopsy, which showed the characteristic histopathological features of DL, including pigment-laden histiocytes and polyclonal plasma cell proliferation. Fever resolved spontaneously one month post-biopsy, with no recurrence during one-year follow-up. Our experience reinforces that DL must be considered in the differential diagnosis of Fever of unknown origin (FUO), and biopsy is key to its identification.