Metaplastic carcinoma of the breast, an intriguing rarity.

Metaplastic carcinoma breast is categorized as a rare heterogenous neoplasm generally characterized by a mixture of adenocarcinoma with dominant areas of spindle cell, squamous and/or other mesenchymal differentiation. To determine the epidemio-demographic and histopathologic characteristics of this rare entity a retrospective study was conducted to review all cases at the Aga Khan University Hospital (AKUH) Karachi, received during 1st January 2000 to 31st August 2005. Twenty-four patients were identified with a mean age at diagnosis of 46.4 (+/-SD 3.8) years, and an age range of 28-68 years. The mean tumor size was 7.9 cm, range 2.0-17.0 cms (+/-SD 4.77). The specimens were mostly obtained by modified radical mastectomy(54.2%) followed by biopsy (29.2%), lumpectomy (8.3%), and total mastectomy (4.2%). Skin ulceration was found in 37.5% cases. Component sub-categorization showed 13 (54.2%) cases of infiltrating ductal carcinoma with squamous metaplasia, followed by 2 (8.3 %) cases with heterologous elements, 4 (16.7%) cases with spindle cell component, 2 cases of matrix producing carcinoma and one case of squamous cell carcinoma. The malignancy was high grade, modified Bloom Richardson's grade III (54.2 %) and grade II (12.5%). Such grading was not applicable to 4 cases of spindle cell component and 1 case with extensive chondroid areas. Twelve patients had information available on the nodal status. Five (41.6%) were node-negative, four (33.33%) had 1-3 lymph node involvement positive, and three (12.5%) had more than 3 lymph nodes positive. The median 3 year Event Free Survival (EFS) was 10% and overall survival was 30%. MCB is an aggressive disease with a poor prognosis. This aspect appears bleaker in our population either due to the biological characteristic of the malignancy in a high risk group or the lack of availability and accessibility of health coverage, resulting in a delayed presentation. MCB is an uncommon breast malignancy and due to the lack of sufficiently large studies there is limited knowledge as to the pathogenesis, progress, best treatment protocols and prognosis. Collaborative studies are therefore recommended to allow for better understanding of this intriguing neoplasm.