Quantitative analysis of mast cells in benign and malignant breast lesions. Immunohistochemical study on formalin-fixed, paraffin-embedded tissues.

BACKGROUND It has been reported that the number of mast cells was significantly greater in malignant breast carcinomas than in benign breast lesions. This was due to tryptase-containing mast cells while tryptase, chymase-containing mast cells had no effect. However, analysis of mast cells in breast carcinomas and benign breast lesions based on their histological findings remains to be elucidated. METHODS Using immunohistochemical methods morphological examinations of mast cells were undertaken in benign and malignant breast tissues from 51 patients (30 benign, 21 malignant), which were formalin-fixed and paraffin-embedded. In the study with malignant breast tissues, samples of malignant tissues and adjacent healthy tissues were obtained from a single patient, and the number of mast cells was compared. RESULTS Among benign breast tissues, the number of mast cells in intracanalicular fibroadenoma was significantly lower than that in pericanalicular fibroadenoma as well as that in mastopathy. The number of mast cells was significantly greater in malignant lesions than that in benign lesions. The number of mast cells in scirrhous carcinoma and that in solid-tubular carcinoma were significantly increased compared with that in adjacent healthy tissues. In addition, the number of mast cells in scirrhous carcinoma was highest among breast carcinomas, and significantly greater than that in papillotubular carcinoma. CONCLUSION We were the first to find the significant lower number of mast cells in intracanalicular breast fibroadenoma when compared with that in pericanalicular fibroadenoma as well as that in mastopathy. Moreover, the number of mast cells in scirrhous carcinoma was significantly greater than that in papillotubular carcinoma.