BACKGROUND: Squamous cell carcinoma (SCC) of the breast is rare. It remains unclear whether a "pure" form of SCC exists or if all known cases actually represent an extreme form of squamous metaplasia within adenocarcinoma. Due to its rarity and controversy over its definition, there are no good data on appropriate management and prognosis. METHODS: All cases of breast carcinoma indexed at our institution were reviewed to identify seven cases where squamous metaplasia was a significant component of the pathologic diagnosis. Slides and electron micrographs were reviewed by a single pathologist. Clinical information was obtained from medical records. RESULTS: These cases support the concept of a disease continuum with varying degrees of squamous metaplasia. When tumors identified as "pure" SCC on light microscopy are subjected to ultrastructural analysis, either separate squamous and glandular cells are present or both histologic features are noted to coexist in the same cell. CONCLUSIONS: Identification of "pure" cases of SCC appears clinically unimportant. All patients presented with advanced disease, thus necessitating aggressive management regardless of histology. Mastectomy was performed due to large tumor size and adjuvant chemotherapy given rather than hormones because of receptor negativity. The mixed histology should direct future drug choice. The role of radiation remains unclear.
BACKGROUND:Squamous cell carcinoma (SCC) of the breast is rare. It remains unclear whether a "pure" form of SCC exists or if all known cases actually represent an extreme form of squamous metaplasia within adenocarcinoma. Due to its rarity and controversy over its definition, there are no good data on appropriate management and prognosis. METHODS: All cases of breast carcinoma indexed at our institution were reviewed to identify seven cases where squamous metaplasia was a significant component of the pathologic diagnosis. Slides and electron micrographs were reviewed by a single pathologist. Clinical information was obtained from medical records. RESULTS: These cases support the concept of a disease continuum with varying degrees of squamous metaplasia. When tumors identified as "pure" SCC on light microscopy are subjected to ultrastructural analysis, either separate squamous and glandular cells are present or both histologic features are noted to coexist in the same cell. CONCLUSIONS: Identification of "pure" cases of SCC appears clinically unimportant. All patients presented with advanced disease, thus necessitating aggressive management regardless of histology. Mastectomy was performed due to large tumor size and adjuvant chemotherapy given rather than hormones because of receptor negativity. The mixed histology should direct future drug choice. The role of radiation remains unclear.