Fine-Needle Cytological Characteristics of Carcinoma Breast with Medullary or Medullary-like Features Masquerading as Dendritic Reticulum Cell Sarcoma: An Attempt to Explore the Reasons for Erroneous Cytologic Interpretation

Abstract

Background: Infiltration of tumors by dendritic reticulum cells (DRC) reflects the host immune defense mechanism. We observed three breast carcinomas cases with dense tumor-infiltrating DRC and lymphocytes in fine-needle aspiration (FNA) smears, leading to cytodiagnosis or differential diagnosis of dendritic reticulum cell sarcoma (DRCS). An attempt was made to find out the reason behind such an erroneous interpretation.

Materials and methods: Between 2009 and 2014, two cases were diagnosed as DRCS of the female breast by FNA cytology and in one case possibility of DRCS was considered along with medullary breast carcinoma (MBC). We compare and contrast the cytomorphological features of these three cases with those of nine cytologically diagnosed MBC.

Results: Cases diagnosed as DRCS or MBC showed singly dispersed tumor cells, nuclear pleomorphism, bare nuclei, prominent nucleoli, and presence of lymphocytes. There was no significant difference between the two groups for discohesive clusters, syncytial clusters, plasma cells, neutrophils, foamy histiocytes, and necrosis. However, there was significant difference for presence of cohesive clusters (0% DRCS and 100% MBC, P = 0.00485), severe degree (+++) of pleomorphism (100% DRCS vs. 11.1% MBC, P = 0.01818), +++ DRC (P = 0.04697), and DRC with ++ to +++ enlarged nuclei (P = 0.03333), and pleomorphic nuclei (P = 0.00833). Two of the three cytologically diagnosed DRCS cases proved to be MBC or MBC-like and one as invasive ductal carcinoma. Six of nine cytologically diagnosed MBC cases with histology proved to be invasive breast carcinomas.

Conclusion: Criteria for cytodiagnosis MBC need a fresh look. Cases with numerous dendritic cells possibly represent MBC.

Keywords: Breast; Medullary-like carcinoma; dendritic reticulum cell sarcoma; fine-needle aspiration cytology; medullary carcinoma.

Figure 1

Fine-needle aspiration (FNA) smears from a 4 × 2 cm, irregular and hard-left breast mass close to areola in a 34-year-old woman, which was noticed 10 days back (Case no: 1). Ultrasonogram revealed a 2.5 × 1.4 cm lobulate hypoechoic mass at 9 O'clock position. The histopathological diagnosis of core biopsy was high-grade medullary-like carcinoma. (a) FNA smears show numerous pleomorphic tumor cells in occasional syncytial clusters but a few single dispersed intermingled with mature lymphocytes (Papanicolaou × 400). (b) Mostly bare nuclei with prominent nucleoli, a sprinkling of lymphocytes and a few dendritic cells with cytoplasmic processes are appreciated. (MGG × 400). (c) A mixture of bare nuclei, cells with dendritic cytoplasmic processes having pleomorphic nuclei and prominent nucleoli and scattered lymphocytes (Papanicolaou × 400). (d) Positive reaction for CD68 in pleomorphic cells (×400). (e) Vimentin positivity in pleomorphic cells and cells with dendritic processes (×400). (f) Dendritic cells are positive for leukocyte common antigen (LCA) (×400). (g) Scattered dendritic cells are positive for S100 (×400). (h) Occasional and a small group (inset) pleomorphic cells were positive for EMA (×400)

Figure 2

FNA smears from a 2.5 cm mass in the upper and outer quadrant of the left breast in a 32-year-old woman (Case No: 2). Cytodiagnostic possibilities were (1) high-grade carcinoma with lymphocytic infiltration (medullary-type) and (2) dendritic reticulum cell sarcoma (DRCS). The histopathological diagnosis segmentectomy specimen was medullary (triple-negative) carcinoma. (a) Pleomorphic bare nuclei intermingled with lymphocytes and plasma cells (MGG × 400). (b) The bare nuclei have prominent nucleoli. A few cells have faint ill-defined cytoplasm. The background shows lymphocytes (Papanicolaou × 400). (c) Occasional groups of cells were positive for CD35 (×400). (d) Occasional cells were positive for CK (×400). (e) Large number of cells, mostly inflammatory cells were positive for LCA (×400). (f) Groups of cells were positive for vimentin (×400). (g) Scattered cells with dendritic cell processes were positive for CD68 (×400). (h) Occasional nuclei showed a positive reaction for PR (original magnification × 400)

Figure 3

A 65-year-old woman presented with a right retro areolar round mass at 6'O clock position measuring 2 cm × 1.5 cm and another mass at the right axillary tail. Cytodiagnosis was highly suggestive of DRCS. The core biopsy revealed a grade-III invasive mammary carcinoma showing dense inflammatory cell infiltration. (a) FNA smears from the retro areolar mass were cellular and showed numerous singly dissociated atypical nuclei having prominent nucleoli intermingled with a few dendritic cells (Papanicolaou × 400). (b) Occasional cells with intact cytoplasm and prominent dendritic cytoplasmic processes containing enlarged atypical nuclei were observed in between the atypical bare nuclei (Papanicolaou × 1000). (c) The dendritic cells were positive for LCA (×400) and rare large abnormal cells with enlarging nuclei and prominent nucleoli (inset) were also [positive for LCA (×1000). (d) Dendritic cells including those with prominent nucleoli were positive for CD68 (×1000). (e) Dendritic cells and atypical cells were positive for vimentin (×1000). (f) Dendritic cells and atypical cells were positive for S100 (×1000)

Figure 4

A 60-year-old woman was subjected to FNA under ultrasound-guidance from a 5 × 5 cm cystic mass situated at 3 O'clock position in the left breast. Cytodiagnosis was medullary carcinoma of the breast. The needle core biopsy of the breast mass was highly suspicious of invasive ductal carcinoma with predominantly lymphoplasmacytic infiltration. (a) Smears prepared from it showed pleomorphic malignant cells with prominent nucleoli in groups as well as a singly dispersed form (MGG × 400). (b) The groups of malignant cells were infiltrated by lymphocytes. Occasional malignant cells also displayed dendritic processes (Papanicolaou × 400). (c) The neoplastic cells were positive for epithelial membrane antigen (×400). (d) The neoplastic cells were positive for pan-CK (×400). (e) Inflammatory cells were positive for LCA but the neoplastic cells were negative (×400). (f) Inflammatory cells were positive for vimentin but neoplastic cells were negative (×400). (g) The neoplastic cells were negative for CD68 but a few inflammatory cells were positive (×400). (h) Most inflammatory cells, likely to be histiocytes, are positive for CD68 (×400). (i) The neoplastic cells were positive for S100 (×400). (j) The inflammatory cells, likely to be histiocytes, were positive for CD68 (×400)