Micropapillary carcinoma of the breast with necrosis-like cell death: a case report.

A primary invasive micropapillary carcinoma of the breast in a 46-year-old woman is reported. Histologically, it was composed predominantly of papillary tumor cell clusters without fibrovascular cores, surrounded by a clear space. Tumor cells were positive for cytokeratin (CK) 7, estrogen receptor (ER), and progesterone receptor (PR), but negative for p53, CK 20, CD34, c-Erb-B2, CK5, epidermal growth factor receptor (EGFR), vimentin, and c-kit. MUC1 expression was found at the reversed apical membrane of neoplastic cell clusters. Accordingly, electron microscopy showed the lack of basement membrane and presence of microvilli at the basal surface of the tumor cells. Moreover, ultrastructural examination revealed single tumor cell death characterized by patchy condensations of chromatin throughout the nucleus. These nuclear alterations were associated with the occurrence of empty cytoplasmic vacuoles, conferring a necrosis-like phenotype to this cell death. Alternative programmed cell deaths are reviewed and their morphologic distinction is discussed.

Morphological changes of follicular cell basal borders and basement membranes in benign and malignant nodular lesions of the thyroid gland: an ultrastructural study.

Microfollicular nodular lesions of the thyroid gland may represent a differential diagnosis problem. Firstly, nodular areas of follicular hyperplasia have to be distinguished from follicular adenomas. On the other hand, nodular microfollicular areas exhibiting large pale nuclei, occasionally found in hyperplastic nodules and follicular adenomas, must be discriminated from latent papillary carcinomas with predominant follicular architecture. The diagnosis of follicular carcinoma still requires the detection of vascular and/or capsular microinvasion. A more refined study was planned to search for additional descriptors useful for diagnosis The authors report the results of an ultrastructural investigation carried out on 220 thyroid nodular lesions and 50 specimens of macroscopically nonnodular glands. An infolding arrangements of the thyreocyte basal border (TBB) and follicular basement membrane (FBM) was demonstrated in 50/50 nonnodular thyroid tissue specimens and 53/67 (79.1%) hyperplastic nodular lesions (p<.005). A linear arrangement of the TBB and FBM was found in 85/121 (70.2%) follicular adenomas and in 32/32 differentiated carcinomas (p<.001). In the last group, 12/32 (37.5%) cases showed focal discontinuities of FBM. In conclusion, the benign thyroid nodules show a prevalently infolding arrangements of TBBs, whereas the majority of proliferative lesions display a linear morphology. In absence of an infiltrating pattern there is no morphological evidence of discriminating potentially malignant vs. benign lesions. The linear distribution of TBBs and FBMs places the case in a group of borderline lesions that involve a more careful postsurgery investigation.