Tumor type and single‐cell/mesothelial‐like cell pattern of breast carcinoma metastases in pleural and peritoneal effusions

Abstract

Invasive ductal and lobular breast carcinomas often have different preferred metastasis sites and distinct histomorphologic characteristics. Their metastatic cytomorphologic cell features in body cavity fluids are generally readily recognized, but the single-cell/mesothelial-like pattern and its relationship to the primary tumor type have not been well studied, nor whether metastases have a propensity for certain body cavity sites on the basis of the primary tumor type. To further assess the tumor type and single-cell pattern of breast carcinoma metastases in pleural and peritoneal effusions, we retrospectively studied 853 pleural and peritoneal effusions and correlated the findings with the primary tumor type. When necessary, the single- cell/mesothelial-like pattern was documented immunohistochemically. Metastatic breast carcinomas represented 249 (50.8%) of 490 pleural and 51 (14.0%) of 363 peritoneal effusions. Most metastases in pleural and peritoneal effusions were ductal carcinomas (92.4% and 62.7%, respectively). Lobular carcinoma accounted for only 2 (0.8%) of 249 pleural and 11 (21.6%) of 51 peritoneal effusions. The single-cell/mesothelial-like cell pattern was found in all lobular carcinomas but also in 11 (6.0%) of 184 reviewed ductal carcinomas (nine pleural and two peritoneal). Awareness of these findings and the use of immunohistochemical analyses are necessary for accurately diagnosing metastatic breast carcinoma, especially lobular type.

Pulmonary Adenocarcinoma in Malignant Pleural Effusion Enriches Cancer Stem Cell Properties during Metastatic Cascade

“…It usually comprises a series of discrete steps and requires the transport of malignant cells via blood and/or lymph vessels. In addition to blood and lymph vessels, body fluid is also a potential means of transportation for cancer metastasis [2]. Involvement of the serous membrane from the primary pulmonary adenocarcinoma causing initial malignant pleural effusion (MPE) usually indicates a late stage of cancer.…”

Metastatic Lobular Carcinoma of the Breast in Pleural Fluid: Diagnostic Pitfall for Mesothelial Cells

“…The single or mesotheliallike cell pattern, which is characterized by cell monotony, eccentric nuclei with plasmacytoid features, secretory vacuoles and intracytoplasmic lumina, is characteristic of metastatic lobular carcinoma although it can be also found in 6.0% of metastatic ductal carcinoma [4]. However, unlike in metastatic lobular carcinoma, most of ductal carcinoma cells show nuclear pleomorphism with overt malignant features.…”

“…Lobular carcinoma is reported to have predilection for peritoneal spread rather than pleural cavity [2,3]. The largest series of metastatic carcinomas in effusions was reviewed by Antic et al, [4] with metastatic lobular carcinoma in only 2 out of 249 cases, (0.8%) in pleural fluid and 21.6% in peritoneal fluid. The cytologic features of invasive lobular carcinoma in fine needle aspiration cytology are relatively well described in the literature.…”

“…Several cytologic patterns of breast lobular carcinoma in body fluid have been described, which includes cannonball or three-dimensional cluster pattern, single-cell or mesothelial-like cell pattern [4][5][6][7]. The single or mesotheliallike cell pattern, which is characterized by cell monotony, eccentric nuclei with plasmacytoid features, secretory vacuoles and intracytoplasmic lumina, is characteristic of metastatic lobular carcinoma although it can be also found in 6.0% of metastatic ductal carcinoma [4].…”

“…Lobular carcinoma of the breast has a greater propensity to metastasize to the leptomeninges, peritoneal surfaces, retroperitoneum, gastrointestinal tract, reproductive organs and bone in contrast to the ductal carcinoma, which shows common metastasis to the lung, liver, brain and pleural cavity [1]. Infiltrating lobular carcinoma is one of the most difficult types to identify in fine-needle aspiration as well as body fluid cytology because of the innocuous appearance of the tumor cells and the lack of cohesive clusters, thus being a frequent cause of false negative diagnosis on cytology especially when the specimen is paucicellular [2][3][4]. It is also known that when the lobular carcinoma metastasizes to the body fluid, the distinction between metastatic carcinoma cells and mesothelial cells can be very difficult.…”