A 26-year-old previously healthy Paraguayan woman consulted because of persistent fever and painful cutaneous lesions of the arms and legs of 2 weeks duration. Physical examination revealed: numerous two cm diameter brown subcutaneous nodules, and ulcers of both feet (left); supraclavicular, axillary and inguinal lymphadenopathy; hepatosplenomegaly; and thermal hypoesthesia and decreased pain sensitivity in legs and arms.
A blood film showed atypical lymphocytes, so a bone marrow aspiration and trephine biopsy were performed. A Ziehl-Neelsen stain revealed numerous acid-fast bacilli (right). A week later, a biopsy of a cutaneous lesion showed panniculitis with mycobacteria and an infiltration by microvacuolated histiocytes, confirming the diagnosis of lepromatous leprosy. The patient was discharged home after clinical improvement with rifampicin, dapsone and clofazimine.
Although the bone marrow is usually affected in lepromatous leprosy, the diagnosis is commonly made by skin biopsy. This case illustrates the importance of bone marrow aspiration in the differential diagnosis of fever of unknown origin.