The significance of extracellular mucin in breast fine needle aspiration specimens.

OBJECTIVE: To determine if all breast fine needle aspiration (FNA) specimens with abundant extracellular mucin require excisional biopsy. METHODS: Fifty cases of breast FNA containing extracellular mucin, reported with a recommendation for biopsy and with histological follow-up were reviewed. Cellular features were noted, and the cases reclassified ignoring the presence of mucin and then correlated with histological outcome. RESULTS: Subsequent histology showed benign changes in 20% (10/50), two cases (4%) of atypical ductal hyperplasia (ADH) and 76% (38/50) to be malignant lesions, including three cases of ductal carcinoma in situ (DCIS). When the FNA cases were reviewed disregarding the presence of mucin, 11 cases were reclassified as benign and one case that contained mucin-like material but no epithelial cells reviewed as non-diagnostic. All cases of invasive mixed and mucinous carcinoma (MC) would have been reported with a recommendation for histological examination. In addition, the three cases each of fibroadenoma (FA) and a benign mucocoele-like lesion (MLL) were correctly identified as benign. However, two cases each of DCIS and ADH would have been reported benign with no recommendation for further histology. CONCLUSIONS: Breast FNA specimens with mucinous material may arise from sampling of a range of benign and malignant processes; however, a biopsy should be recommended, even in cases of low cellularity, owing to sampling problems and the frequent co-occurrence of significant lesions. FNA is highly accurate at predicting carcinoma with mucinous differentiation although it is not possible to reliably predict if the lesion represents pure MC or a mixed carcinoma.

The varied presentation of metastatic melanoma in fine needle aspiration cytology of the breast.

OBJECTIVE: To identify cytomorphological patterns of metastatic melanoma (MM) in breast fine needle aspiration (FNA) specimens and highlight the differential diagnoses and features most useful in identifying MM. METHODS: The clinical, radiological and FNA findings of 16 cases were reviewed. Cytological features evaluated related to cell arrangement, size and shape of cells, nuclear and cytoplasmic features, and the presence or absence of necrosis. RESULTS: The series consisted of 14 females and two males, ranging in age from 24 to 83 years (mean = 50 years). A previous history of melanoma was available in 12/16 (75%) cases at the time of FNA reporting; however the clinical/radiological impression in 4/16 cases was of a breast cyst. The cases were classified into six morphological variants: classical (8/16), pseudopapillary (3/16), spindle-cell (1/16), melanin-rich (1/16), pleomorphic (2/16) and lymphoma-like (1/16). The varying patterns raised a wide range of differential diagnoses; however, discohesion, binucleation and granular cytoplasm were the major features seen in 94% of all cases. In 14/16 cases (88%), plasmacytoid cells, prominent nucleoli and cytoplasmic vacuolation were identified. Melanin and multinucleation were detected in 44% of cases and intranuclear cytoplasmic invaginations in 63%. Necrosis was present in more than half of the cases (56%). CONCLUSION: MM should be considered in the differential diagnosis of breast FNA specimens when atypical cells are seen that present as plasmacytoid cells in a dispersed or pseudopapillary pattern, or as spindle, pleomorphic or pigmented cells. These features, combined with clinical history and immunocytochemistry, may assist in correctly identifying MM and directing optimal treatment.