A necrotic adult male filaria was found in sections of a dense, fibrous, subcutaneous nodule excised from below the breast of a 61-year-old woman, resident of Mie Prefecture in Honshu, Japan. Owing to its necrotic condition, and to a lack of essential knowledge of the comparative micro-anatomy of filarial worms, a differentiation between Dirofilaria and Dipetalonema species, or member of a related group, was not possible.