[1321] Squamous Morular Metaplasia in Non-Intestinal Type Sinonasal Adenocarcinoma and Seromucinous Hamartomas: A Novel Immunophenotypic Pitfall

Bibianna M Purgina, Jassem M Bastaki, Raja R Seethala. University of Pittsburgh Medical Center, Pittsburgh, PA

Background: Non-intestinal type sinonasal adenocarcinomas (non-ITAC) and intestinal type adenocarcinomas (ITAC) are rare biologically distinct sinonasal tumors that can be immunophenotypically distinguished using markers like CK7, CK20, and CDX2. We had surprisingly noted one case of sinonasal seromucinous hamartoma (SSH), a potential precursor to non-ITAC, which showed focal CDX2 immunoreactivity in association with squamoid morules. To survey this potential diagnostic pitfall, we evaluated the morphologic and immunohistochemical characteristics of a series of SSH, non-ITAC, and ITAC.
Design: Three SSH, fifteen (9 low grade (LG), 6 high grade (HG)) non-ITAC (5 papillary, 3 lobular, 2 cystic, 4 solid and 1 cribriform), and sixteen ITAC (4 papillary, 5 colonic, 1 solid, 6 mucinous) were retrieved from our files. One case of SSH arising in left middle turbinate was associated with a non-ITAC of the right sinonasal cavity. Histologic features, including growth pattern, metaplastic changes, and immunohistochemical profile were tabulated.
Results: All SSH (3/3) were CK7 positive, S100 positive, and CK20 negative. One SSH with morular metaplasia showed CDX2 positivity restricted to morules. All ITACs tested were CK20 positive (10/10), CDX2 positive (6/6), and 9/10 were CK7 positive. Squamous or morular metaplasias were not seen in ITAC. All non-ITACs tested were CK7 positive and CK20 negative (9/9). A subset of LG non-ITACs (3/5) were S100 positive, similar to SSH, and DOG1 (an acinar selective marker) positive. Three cases showed squamoid features accompanied by focal p63 and CK 5/6 reactivity. One non-ITAC with metaplasia showed morules with CDX2 and nuclear beta-catenin positivity. The other cases with squamous metaplasia were CDX2 negative.
Conclusions: SSH and non-ITAC add to the list of glandular lesions that may show morular metaplasia. Similar to other tumors, the morules are characterized by nuclear beta catenin and CDX2 reactivity which is a potential diagnostic pitfall in the sinonasal tract. However, the restriction to morules and lack of CK20 reactivity distinguish SSH/non-ITAC with morular metaplasia from ITAC. The shared morphology and immunophenotype between SSH and a subset of non-ITAC supports an etiologic relationship between these entities.
Category: Head & Neck

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 204, Monday Morning

 

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