Lymphocutaneous type of nocardiosis caused by Nocardia brasiliensis: a case report and review of primary cutaneous nocardiosis caused by N. brasiliensis reported in Japan

Nocardiosis is a mixed suppurative and granulomatous inflammatory disease caused by infection with Nocardia organisms, a group of aerobic actinomycetes. We recently encountered a 25-year-old woman with posttraumatic nocardiosis of the lower extremities. The clinical symptoms noted during her first visit included erythematous swelling of the right knee accompanied by white maceration of the center of the knee and erosions, shallow ulcers and satellite pustules. In addition, multiple erythematous areas (up to the size of the tip of the thumb) were linearly distributed on the right thigh. These lesions were painful, and right inguinal lymphadenopathy was also noted. No lesion was found in internal organs such as the lungs. Histopathologically, signs of nonspecific granulomatous inflammation were observed, as well as several filamentous branching bacilli positive on Grocott stain. The organisms isolated from culture of pus were acid-fast, Gram-positive long rods. The isolated strain was finally identified as Nocardia brasiliensis. The patient was therefore diagnosed with lymphocutaneous type of primary cutaneous nocardiosis caused by N. brasiliensis. Drip infusion of flomoxef sodium was initially performed to treat her condition. Because of exacerbation of erythematous swelling of the right knee and an increase in number of pustules, treatment was switched to oral minocycline hydrochloride therapy. The disease healed 9 weeks after the start of oral minocycline hydrochloride therapy. Our patient was free of systemic immunosuppression and was neither under 10 nor over 65 years of age. She may therefore be considered a rare case of lymphocutaneous type of nocardiosis. We present this case and discuss reported cases of primary cutaneous nocardiosis due to N. brasiliensis in Japan.