Abstract :
Introduction: Mucinous (colloid) carcinoma (MC) of the breast is relatively rare and accounts for 1-6% of all breast cancers. Traditionally, pure mucinous tumors and mixed infiltrating ductal carcinomas with a mucinous component have been described. Pure mucinous carcinoma of the breast has a favorable prognosis than the mixed variety noted in several studies. The common age of presentation is the postmenopausal group. Cytological diagnosis of these tumors is challenging.
Materials and Methods: A retrospective study was conducted at our institute. 22 cases consisting of both mixed and pure mucinous carcinomas diagnosed by cytology and verified on histopathology between January 2007 and November 2015 were included in the study. All cytology and histopathology slides were reviewed.
Results & Discussion: A total of 22 cases were evaluated. The age ranged from 34-78years. The left breast was involved in 12 cases and the right breast in 10cases. 19 cases were diagnosed as mucinous carcinoma on cytology. However 12 of these cases were reported as pure mucinous carcinoma on biopsy.
All these cases displayed abundant mucin, small nuclei and/or regular nuclear outlines on cytology. 7 cases turned out to be mixed tumors on histopathology. Sparse mucin, large nuclei, irregular nuclear outlines or the presence of nucleoli were found in mixed mucinous carcinomas but not in pure tumors. Three cases were diagnosed as infiltrating ductal carcinoma (IDC) on cytology. One of these patients had 2 nodules, diagnosed on histopathological examination as IDC and mucinous carcinoma. Out of the other two cases, 1 case was diagnosed as cellular variant of mucinous carcinoma and another case as mixed carcinoma
on biopsy. Cellular variant of mucinous carcinoma can mimic low grade ductal carcinoma on cytology. A thorough examination of the slides for mucinous material and few thin capillary fragments provide a valuable diagnostic clue.
Conclusion: The distinction between pure and mixed mucinous carcinoma is important, because patients with the former type have a much favorable prognosis, with a low propensity for lymph node and distant metastasis. Cytopathological identification of patients with pure mucinous carcinomas may be performed only in a limited number of cases. The various differential diagnosis should always be kept in mind while dealing with lesions associated with mucin. However the age of presentation, clinical features and radiological findings can help to further categorize the various mucinous lesions.
Keyword :
Carcinoma,Breast, Cytology.