[672] Polyglucosan Bodies Are an Overlooked but Prevalent and Diagnostically Useful Feature of Gastrointestinal Tract Leiomyomas

Jaclyn F Hechtman, Noam Harpaz. Mount Sinai School of Medicine, New York, NY

Background: Elliptical, basophilic intracytoplasmic inclusions termed polyglucosan bodies (PBs) are an enigmatic but histologically distinctive feature of some intestinal myopathies. We have observed similar inclusions in gastrointestinal (GI) leiomyomas (LMs). The goal of this study is to investigate their anatomic distribution, prevalence and diagnostic value in distinguishing LMs from GI stromal tumors (GISTs).
Design: All available H&E slides of 35 complete or partial LM resection specimens (8 esophageal, 7 gastric, 2 small intestinal, 18 large intestinal), 19 resected GISTs of low malignant potential (12 gastric, 7 small intestinal), and 10 uterine leiomyomas were examined for PBs. Identification of PBs was readily achieved with H&E and confirmatory positive staining with DPAS and Alcian blue was performed in a subset of cases (fig. 1, original magnification (a) x400, H&E; (b) x600, DPAS).

Diagnoses of LM and GIST had been routinely established immunohistochemically. Dimensions were obtained from clinical records, gross descriptions and microscopic measurements.
Results: The LMs and GISTs had mean diameters of 1.8 cm (range 0.05 - 9.0 cm) and 3.1 cm (range 1.2 - 6.0 cm), respectively. PBs were identified in 13/35 GI LMs (37%), including 7/14 LMs (50%) of diameter 1.0-9.0cm and 6/21 LMs (29%) of diameter 0.05-0.8cm. Their anatomical prevalence was esophagus, 4/8; stomach, 5/7; small intestine, 1/2; large intestine, 3/18. PBs were not identified in any GISTs {P=0.0029} or uterine LMs {P=0.0223}. In sections of LMs with PBs, the density ranged from 1 PB per 4 mm2 to 1 PB per 200 mm2. No size, gender or age differences were noted between resected LMs with and without PBs. PBs occurred in muscularis mucosae- and muscularis propria-based GI LMs.
Conclusions: PBs are a prevalent yet hitherto overlooked feature of GI tract LMs that are absent from GISTs. Their identification on routine histology permits distinction of LMs from GISTs of low malignant potential, obviating the need for immunohistochemical stains.
Category: Gastrointestinal

Wednesday, March 21, 2012 9:30 AM

Poster Session V # 65, Wednesday Morning

 

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