Page 47 - AAOMP Meeting 2019

POSTER ABSTRACTS - TUESDAY, JUNE 11, 2019

#45 A CASE OF A RECTAL NEUROENDOCRINE CARCINOMA METASTASIZING TO
THE PAROTID GLAND
Dr. Kelcie Barnts (Department of Diagnostic Sciences, Texas A&M University College of
Dentistry, Dallas, Texas), Dr. A. Joe Saad (Methodist Health System), Dr. Yi-Shing Lisa Cheng
(Department of Diagnostic Sciences, Texas A&M University College of Dentistry, Dallas, Texas),
Dr. John Wright (Department of Diagnostic Sciences, Texas A&M University College of Dentistry,
Dallas, Texas), Dr. Paras Patel (Department of Diagnostic Sciences, Texas A&M University
College of Dentistry, Dallas, Texas)
We report a case of a neuroendocrine carcinoma of the rectum that metastasized to the parotid gland of a 48-
year old male. The patient presented with a parotid mass. The patient had a history of squamous cell
carcinoma of the forehead, a neoplasm of uncertain behavior of the head of the pancreas, and a neuroendocrine
carcinoma of the rectum. Attempts were made to obtain the slides for the rectal neuroendocrine carcinoma
without success. The parotid tumor was divided into lobules by fibrous connective tissue bands. The neoplastic
cells were predominantly polyhedral with abundant eosinophilic cytoplasm, often plasmacytoid in appearance.
The nuclei ranged from small hyperchromatic and pyknotic to more vesicular. Stains for chromogranin,
creatinine kinase, muscle (MCK), insulinoma-associated protein 1 (INSM1), S100, and synaptophysin were
positive. Alpha-1 antitrypsin (A1AT), cytokeratin (CK) 7, melanoma antigen (melanA), tumor protein 63
(p63), smooth muscle actin (SMA), and smooth muscle myosin (SMM) stained negatively. There was a low
Ki-67 proliferative index of approximately 5%. The report of the rectal neuroendocrine adenocarcinoma
showed that the tumor cells were positive for Cytokeratin (CK) AE1/AE3 and synaptophysin and had patchy
positive staining for prostatic acid phosphatase (PSAP). Staining was negative for CK7, CK20, Caudal Type
Homeobox Type 2 (CDX2), thyroid transcription factor 1 (TTF-1), chromogranin, prostate specific antigen
(PSA), and Prostate-specific membrane antigen (PSMA). The Ki-67 was reported as low. The diagnostic
challenges of this rare metastatic neuroendocrine carcinoma will be presented as well as a discussion of
primary versus metastatic neuroendocrine carcinomas of the parotid.

#46 DIATOM-ASSOCIATED FOREIGN-BODY REACTION MIMICKING AN
INflAMMATORY ODONTOGENIC LESION: A REPORT OF TWO CASES
Dr. Thabet Alhousami (Boston University), D r. Devaki Sundararajan (Boston University), Dr. Jeremy
Lassetter (Adirondack Oral & Maxillofacial Surgery), Dr. Yuri Shamritsky (North Shore &
Brookline Endodontics), Dr. Sadru Kabani (Stratadx), Dr. Vikki Noonan (Boston University)
Foreign body reactions in the oral cavity are common and are often the result of exogenous material
introduced following either iatrogenic or traumatic injury provoking a distinctive immune response. To the
best of our knowledge we describe the first two cases of a granulomatous foreign-body reaction to diatoms,
single-celled algae belonging to the taxonomic phylum Bacillarophyta, involving the jaws. In both instances
the clinical presentation mimicked a lesion of inflammatory odontogenic etiology. The morphologic features
of diatoms and a comprehensive literature review are provided. The diagnosis of a diatom-associated foreign
body reaction necessitates familiarization with the histopathologic features, a sufficient degree of suspicion,
and clinicopathologic correlation.