Cytomorphological features of cystic neutrophilic granulomatous mastitis on ThinPrep

Ami Patel, Simon Sung, Syed A. Hoda, Lars F. Westblade, Timothy D'Alfonso, Rema Rao

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Granulomatous mastitis (GM) is an uncommon entity and challenging to distinguish from breast carcinoma, both clinically and upon imaging. Cystic neutrophilic granulomatous mastitis (CNGM) is a histologically distinct GM with clear “cystic” spaces (CS) surrounded by neutrophils and may contain Gram-positive bacilli (such as Corynebacterium species). Cytologic features of GM, in particular CNGM, on ThinPrep (TP), are limited. We reviewed the cytological features of GM with a special focus on CNGM on TP. Ten cases with a concurrent/recent FNA and histologic diagnosis of GM or CNGM, or positive culture for Corynebacterium kroppenstedtii, were identified over an 11-y period (2007-2017). A double-blinded review of the TP slides was performed by two independent cytopathologists. Data were analysed using Fisher's exact test. Six cases were histologically proven CNGM and 1 FNA only case had a positive culture for C. kroppenstedtii. Three had a histological diagnosis of GM. TP from the 7 CNGM cases demonstrated CS, including 1 case with a cellblock (CB) study showing well-formed clear CS, while none of the non-CNGM cases had CS (P =.01). Bacteria were identified within CS in 5 of 7 cases of CNGM. Multinucleated giant cells, granulomas, histiocytes, and neutrophils were variably observed. All histologically confirmed cases of CNGM showed distinct CS on TP. Cellblock study is a valuable adjunct to evaluate CNGM and for ancillary studies. Although our study was limited by a small sample size, our findings necessitate the need for studies with a larger cohort.

Original languageEnglish (US)
Pages (from-to)966-970
Number of pages5
JournalDiagnostic Cytopathology
Issue number11
StatePublished - Nov 2018
Externally publishedYes


  • ThinPrep
  • corynebacterium
  • cystic neutrophilic
  • granulomatous mastitis

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology


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