Fine-Needle Aspiration of Epithelial-Myoepithelial Carcinoma of the Parotid Gland With Prominent Adenoid Cystic Carcinoma-Like Cribriform Features: Avoiding a Diagnostic Pitfall.
OBJECTIVE
Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland malignancy associated with an overall good prognosis. Fine-needle aspiration (FNA) typically shows a dual population of myoepithelial and ductal cells. Rarely, acellular matrix globules are present, raising a differential diagnosis of adenoid cystic carcinoma (AdCC), a more aggressive salivary gland malignancy associated with a poor long-term prognosis. We report an FNA case of EMC containing a predominant pattern of AdCC-like spherical globules.


METHODS
We compare features of an unusual case of EMC with those of cribriform AdCC to arrive at morphologic clues to the correct diagnosis.


RESULTS
Distinguishing features of EMC on FNA include (1) a prominent population of myoepithelial cells vs the predominance of basaloid cells in AdCC and (2) cohesive matrix globules with a peripheral rim of pale-staining basement membrane material compared with the dyscohesive matrix globules of AdCC. Immunochemical markers (S100, CD117, and MyB) are also useful.


CONCLUSIONS
Although EMC and AdCC can both contain spherical matrix globules, close evaluation of the cytomorphology of the globules and their relationship to surrounding cells provides a clue to distinguish the two neoplasms.
From the Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston oaisagbonhi@partners.org.
Omonigho A
OA
Aisagbonhi
Department of Pathology, North Shore Medical Center, Salem, MA.
Mark A
MA
Tulecke
From the Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston.
David C
DC
Wilbur
Department of Pathology, Lahey Hospital and Medical Center, Burlington, MA.
Atoussa
A
Goldar-Najafi
Department of Pathology, Lahey Hospital and Medical Center, Burlington, MA.
Shams
S
Iqbal
From the Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston.
Peter M
PM
Sadow
From the Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston.
William C
WC
Faquin
D000368:Aged; D044963:Biopsy, Fine-Needle; D002277:Carcinoma / Q000175:diagnosis* / Q000473:pathology; D003528:Carcinoma, Adenoid Cystic / Q000175:diagnosis* / Q000473:pathology; D003937:Diagnosis, Differential; D004847:Epithelial Cells / Q000473:pathology; D006801:Humans; D008297:Male; D010307:Parotid Neoplasms / Q000175:diagnosis* / Q000473:pathology
Adenoid cystic carcinoma; Epithelial-myoepithelial carcinoma; Fine-needle aspiration; Salivary gland