Background: The behavior of some of the rare types of breast cancer is not well understood.
Objective: To study the presentation, pathology, and outcome of some of the rare types of breast cancer.
Methods: Rare types of breast cancer cases seen at King Fahd Hospital from 2008 till April 2016 were reviewed.
Results: There were 209cases of breast cancer seen over 8 years; 6 of them were of the rare types. A case of primary signet-ring cell carcinoma (SRCC) presented with wide spread skeletal and lung metastases. Histologically, it assumed lobular growth pattern with abundant intra-cytoplasmic mucin giving the signet ring appearance. The second case was glycogen-rich clear cell carcinoma (GRCC) with solid ductal carcinoma in situ clear cell type. The patient presented with a 2 cm breast mass with no axillary lymph node involvement. Histologically, the cells were polygonal with eosinophilic cytoplasm and distinct borders and the invasive component formed a stromal lobular growth pattern. The third case was a pure epithelial squamous cell carcinoma (SqCC) with axillary lymph node metastases. The patient presented with a rapidly enlarging breast mass with skin infiltration but no ulceration. Histologically, it was metaplastic carcinoma with pure high-grade squamous epithelial cells with glassy keratinization. The fourth case was a low grade peri-ductal stromal sarcoma (PDSS) with subsequent short-term local recurrence as a high-grade lesion. Histologically, it showed ductular units surrounded by moderately cellular spindle cell mesenchymal proliferation. The fifth case was a young (42 years old) patient presenting with a rapidly enlarging well-defined 6 cm cystic mass. The bloody aspirate was cytologically inconclusive and the cyst rapidly collected so it was completely excised. Histologically it was found to be triple negative high grade intra-cystic solid papillary carcinoma. The sixth case was a newly developed firm mass in a 32 years old lady with Silicone filled breast prosthesis. Ultrasound showed a well-defined solid lesion resembling fibroadenoma. Tru-cut needle biopsy showed adenoid cystic carcinoma with salivary gland features of basal phenotype without the involvement of axillary lymph nodes.
Conclusion:These rare types of breast cancer require skilled pathologic interpretation which is currently the only tool to predict their prognosis. They lack specific clinical or radiologic diagnostic features.