Cytohistologic features of invasive micropapillary carcinoma in a young female

Fine needle aspiration cytology of invasive micropapillary carcinoma of the breast

AIM

To determine the pathognomonic diagnostic cytological features of invasive micropapillary carcinoma of the breast which is a poor prognostic subtype of infiltrating ductal carcinoma.

METHODS

A series of 20 histologically proven tumours were reviewed retrospectively to evaluate the various cytological features, including tumour morules, isolated malignant cells, staghorn epithelial structures, mucinous background and apocrine metaplasia.

RESULTS

Tumour morules formation and isolated malignant cells were the two most reliable and constant cytological features, being present in 75% (15/20 cases) of cases. Staghorn epithelial structures were present in 35% (7 cases). Mucinous background (2 cases, 10%) and apocrine metaplasia (4 cases, 20%) of the tumour cells were seen in a few cases only and did not appear very helpful.

CONCLUSION

Tumour morules formation, isolated malignant cells and staghorn epithelial structures are the most reliable cytological features, and the presence of these should raise suspicion of invasive micropapillary carcinoma.

Fine-needle aspiration cytology of medullary breast carcinoma: report of two cases and review of the literature with emphasis on differential diagnosis

Medullary carcinoma is a rare variant of breast carcinoma with a relatively good clinical prognosis as strictly defined. Characteristic features on fine-needle aspiration cytology (FNAC) allow medullary carcinoma to be considered in the cytologic differential diagnosis. We present two FNAC cases with such features, including high cellularity with clusters and single intact malignant cells, bizarre stripped nuclei with prominent nucleoli in a lymphoplasmacytic background, and illustrate one case in liquid-based preparation. Surgical excision revealed that one patient had medullary carcinoma, while the second patient had high-grade infiltrating ductal carcinoma. Breast FNAC samples with syncytial fragments, bizarre nuclei with prominent nucleoli, and a chronic inflammatory infiltrate should raise the possibility of medullary carcinoma. However, the differential diagnosis also includes high-grade ductal carcinoma, lymphoma, or metastasis to breast or intramammary lymph nodes; thus, histopathologic analysis is required for definitive diagnosis.

Fine-needle aspiration cytology findings of an uncommon micropapillary variant of pure mucinous carcinoma of the breast: review of patients over an 8-year period

BACKGROUND

Previous attempts at subclassifying pure mucinous carcinomas of the breast based on architectural patterns and other associated features are on record. A distinctive micropapillary variant with most tumor cells arranged in micropapillae/pseudoacini has not been described previously.

METHODS

The author reviewed the histologic slides from all 556 patients who underwent wide excision/mastectomy for mammary ductal carcinoma, either in situ or invasive, at Pamela Youde Nethersole Eastern Hospital, Hong Kong, during an 8-year period from early 1994 to the end of 2001. Five patients with pure mucinous carcinoma with diffuse micropapillary architecture were noted. The cytologic features (if available) were correlated with clinical, radiologic, and pathologic findings.

RESULTS

Among the five patients with pure mammary mucinous carcinoma (micropapillary variant), three patients underwent preoperative fine-needle aspiration biopsies and had specimens available for review. The direct smears and cytospin preparations were of moderate cellularity and showed cohesive clusters and micropapillae of mildly pleomorphic tumor cells among a mucoid background. True tumor papillae with fibrovascular cores were not present. Nuclear hobnailing was observed commonly, and occasional psammoma bodies were found. There were also scanty isolated tumor cells scattered around. The pseudoacinar pattern was appreciated more readily in the cell block sections. Histologic examination of the surgical specimens showed features of pure mucinous carcinoma with diffuse micropapillary architecture. The micropapillary arrangement was confirmed further by the demonstration of a reverse polarity immunostaining pattern for epithelial membrane antigen and the identification of microvilli rimming the periphery of tumor cell clusters under the electron microscope. Peritumoral lymphovascular permeation and ipsilateral axillary lymph node metastasis was found in one of the patients.

CONCLUSIONS

The micropapillary variant of mammary mucinous carcinoma demonstrates characteristic cytologic and histologic features that warrant special attention. It may represent the mucinous counterpart of invasive micropapillary carcinoma. Further analysis of a larger series of patients, however, will be required to delineate its prognostic significance, especially its propensity for lymph node metastasis.

Fine-needle aspiration biopsy of invasive micropapillary carcinoma of the breast: a report of five cases

Invasive micropapillary carcinoma of the breast is an uncommon variant of infiltrating ductal carcinoma. Observing its distinctive cytologic appearance and aggressive behavior is important for early diagnosis by fine-needle aspiration cytology (FNAC). There are only a few reported cases in the literature. Five women presented with breast masses. FNAC showed malignant epithelial tumors, and mastectomy materials showed invasive micropapillary carcinoma for all of them. Three patients had axillary lymph node metastases. Invasive micropapillary carcinoma, with its angulated papillary clusters lacking a fibrovascular core, and irregular crowded nuclei, has a distinctive cytologic appearance which correlates with its histological features. A differential diagnosis from other primary or metastatic papillary lesions of the breast may be possible using immunohistochemistry and some cytologic features. The limited experience with invasive micropapillary carcinoma should not discourage others from undertaking further studies.