Delayed reaction after an octopus bite showing a giant cell-rich granulomatous dermatitis/panniculitis.

Adequate clinical data and a sufficient workup, in addition to the histopathological findings, are frequently required to make a correct diagnosis of granulomatous dermatitis/panniculitis. These lesions with an unexpected etiology may include delayed hypersensitivity granulomatous reactions to various factors, such as metals or marine animal injuries. A 50-year-old male presented with multiple subcutaneous nodules on his right forearm 1 month following an octopus bite at his right wrist. After the disappearance of these lesions, which responded well to low-dose oral prednisone, another type of skin lesion characterized by small, numerous papules reappeared on his right forearm. Histopathologically, a specimen from a subcutaneous nodule showed mostly lobular granulomatous panniculitis, which showed an extensive diffuse infiltrate composed of numerous multinucleated giant cells and epithelioid cells intermingling with lymphocytes and eosinophils. A specimen from a papule that subsequently developed disclosed a diffuse granulomatous dermatitis composed of similar cells and also showed granuloma annulare-like features. This case is considered to be a delayed reaction after an octopus bite showing an unusual giant cell-rich granulomatous dermatitis/panniculitis. Octopus bites should therefore be included among the marine animal injuries, which cause a delayed-type reaction with granulomatous dermatitis/panniculitis.