Abstract:

Three cases of swimming pool granuloma are reported. Case 1: a 40-year-old female presented with a 2-month history of nodules and plaques on the right hand and forearm. She was a tropical fish salesperson but denied trauma history. Skin examination revealed multiple irregularly sized, dark-red nodules and plaques on the joints of right fingers, wrist, and elbow, as well as multiple subcutaneous nodules simulating strings of beads on the right upper limb. Case 2: a 48-year-old female presented with a 2-month history of nodules and plaques on the left hand and forearm. There was a history of trauma due to tropical fish tank and filter cleaning. Physical examination showed multiple deep purple plaques and painless subcutaneous nodules scattered on the left hand, wrist, and upper limb. Case 3: a 39-year-old male presented with a 3-month history of nodules on the fingers of both hands. There was no history of trauma, but he was a tropical aquarist. Skin examination revealed multiple soybean-sized dark-red nodules on the extensor aspect of interphalangeal joints of both hands. Fungal examinations yielded negative results in the 3 cases, while histopathology revealed infectious granuloma with a mixed inflammatory cell infiltrate. All of the cases showed positive results in purified protein derivative （PPD） skin test. Mycobacterium marinum was isolated from the lesional tissue of Case 1 and 2, but not from Case 3. All the patients were diagnosed with swimming pool granuloma, and given anti-atypical mycobacterial therapy including oral rifampin and clarithromycin. The lesions disappeared after 1 to 3 months of treatment, with the treatment course varying from 2 to 5 months. No recurrence was observed during a 3- to 12-month follow-up.

Key words: Pathologic processes