Characterizing "blue blobs". Immunohistochemical staining and ultrastructural study.

OBJECTIVE: To investigate the nature and origin of "blue blobs" (Bbs) in atrophic Pap smears in postmenopausal women and to study their clinical significance. STUDY DESIGN: A retrospective study of 412 atrophic Pap smears from postmenopausal women was done to detect the presence of Bbs. The smears from 24 cases showing Bbs were further studied to evaluate the nature of the Bbs with special stains, immunohistochemistry and electron microscopy. RESULTS: Bbs showed a heterogeneous morphology, with variable numbers and staining intensity. The diameter of Bbs was approximately equivalent to that of a parabasal/intermediate squamous cell. Special stains showed Bbs to be positive for periodic acid-Schiff and methyl green pyronin and negative for mucicarmine and calcium. Immunohistochemistry revealed Bbs to be positive for cytokeratin, epithelial membrane antigen and carcinoembryonic antigen and negative for vimentin and muscle-specific actin. Some Bbs had residual ghost nuclear shadows. Electron microscopy revealed cellular skeletons with residual tonofilaments enmeshed within a loose cytoskeleton matrix and nuclei with variable degrees of degeneration. CONCLUSION: Special stains, immunohistochemistry and electron microscopy indicated that Bbs represent parabasal/intermediate squamous cells exhibiting various degree of degeneration. In general, Bbs appear to be of no clinical significance except as a source of potential diagnostic error.

Cellularity of lobular carcinoma and its relationship to false negative fine needle aspiration results.

OBJECTIVE: To evaluate the cytocellularity and histocellularity of lobular carcinoma (LC) and the relationship to high false negative results of fine needle aspiration cytology (FNAC). STUDY DESIGN: In this retrospective study, cellularity was studied in 60 cases of classic LC, LC variants and lobular carcinoma in situ, comparing cytologic smears to their corresponding histologic sections. The cytologic smears were grouped into acellular, low, moderate and high categories, and the histologic sections were grouped into low, moderate and high categories. RESULTS: Malignancy or suspicion of malignancy was diagnosed in 78% of cases. Overall cytocellularity showed acellularity or low cellularity in 60% of cases, while overall histocellularity showed moderate or high cellularity in 95% of cases. When the cytocellularity was moderate or high, the corresponding histocellularity always showed moderate or high histocellularity. When the cytocellularity was low, the corresponding histology showed low histocellularity in 6.3% of cases. Thus, in acellular and low cellular aspirations, corresponding histocellularity may not be the contributing factor toward low cellular yield. In this study, 22% of cases were diagnosed as false negative, 40% were diagnosed as suspicious, and 38% were called positive. Only 17% of positive cases were diagnosed as LC. A large number of LC were misdiagnosed by FNAC as duct cell carcinoma, and most cases of low histocellularity were of the classic type. CONCLUSION: The results of this study suggest that in the majority of cases of LC, cellular yield of FNAC is disproportionately lower than expected when compared to the corresponding histocellularity. Awareness of modest cellularity and subtle cytologic features will aid in the correct preoperative diagnosis of LC, and false negative diagnoses can be minimized.

Cytomorphologic features of classic and variant lobular carcinoma: A comparative study.

There are several subtypes of lobular carcinoma (LC), and their cytomorphologic features differ from classic lobular carcinoma (CLC). The finer details of the differences between CLC and variant lobular carcinoma (VLC) have not been adequately studied. A comparative study of 54 cases of CLC and VLC was done in order to verify any statistically significant differences between them. All cases had histologic confirmation of the diagnosis. Six parameters, which included cellularity, signet-ring cells, intracytoplasmic lumina (ICL), anisonucleosis, cell size, and prominent nucleoli, were studied. The only statistically significant findings were cellularity and cell size when compared to CLC. The cellularity in VLC was higher and the cells in VLC were larger when compared to CLC. There are no definite diagnostic features to identify VLC; however, in a cellular specimen with plenty of large cells with other features of LC, one should have a high index of suspicion of VLC.