Multinucleated mammary stromal giant cells: a benign lesion that simulates invasive carcinoma.

Multinucleated stromal giant cells were found in breast tissue from 14 patients treated by mastectomy for carcinoma over 3 decades (1950s to 1970s). Nine cases were found in a review of 200 consecutive mastectomies (4.5%) performed in 1978. The average age was 51 years with nine patients in their 40s. Other than the age distribution, no association with marital status, family history of breast carcinoma, hormone usage, tumor type, or stage of disease was observed. This benign lesion of undetermined significance should not be misinterpreted as invasive carcinoma. Multinucleated stromal giant cells have been observed in breast specimens from patients not known to have carcinoma at the time of biopsy. These patients had a similar age distribution as those with concurrent carcinoma. Follow-up will be required to determine if the association with carcinoma is significant or merely a coincidence reflecting age or some other yet to be identified factor.