Q fever: a new cause of 'doughnut' granulomatous lobular panniculitis.

Q fever is an uncommon zoonotic rickettsial disease with no exanthem or specific cutaneous lesions. Only nonspecific cutaneous involvement has been reported to date. A 69-year-old Spanish woman with chronic myelogenous leukaemia developed fever and two subcutaneous nodules. The patient complained of extreme pain. Biopsy revealed a granulomatous lobular panniculitis with a characteristic 'fibrin ring' or 'doughnut' appearance: fibrin and inflammatory cells arranged around a central clear space. Changes of membranous lipodystrophy were also found. Q fever serological studies were positive. Our patient had panniculitis with singular histopathological features. These histopathological changes have been described in liver and bone marrow of patients with Q fever. To the best of our knowledge, this cutaneous involvement due to Q fever has not previously been described in the literature.