[621] Interstitial Cells of Cajal in Gastrointestinal Leiomyoma

Anita Deshpande, Vikram Deshpande, Michael J O'Brien. Boston Medical Center, Boston, MA; Massachusetts General Hospital, Boston, MA

Background: Leiomyomas (LM) of the gastrointestinal tract arise within the muscularis mucosae (superficial) and muscularis propria (deep). There are isolated reports of CD117 positive cells, presumed interstitial cells of Cajal (ICC) within gastrointestinal leiomyomas. We have encountered esophageal LM with high proportion of CD117 and DOG1 positive spindle shaped cells, an appearance that mimicked gastrointestinal stromal tumor (GIST). Our aim was to explore the prevalence of ICC in LMs of the gastrointestinal tract and to explore the etiopathogenic significance of these cells in this benign neoplasm.
Design: We identified 30 eophageal LMs, 7 gastric LMs and 3 small bowel LMs (all lesions in muscularis propria). We performed immunohistochemical stains for desmin, CD117 on these neoplasms. In addition immunohistochemical stains for DOG-1 (n=10), CD34 (n=10), and mast cell tryptase (n=4) were performed. We also evaluated a selected cohort (n=12) of superficial colonic LMs. ICC were distinguished from mast cells based on morphology (elongated and occasionally branching spindle shaped cells) and the presence of DOG-1, and CD34 reactivity and absence of tryptase activity.
Results: There were 22 males and 18 females. The mean age was 56 years. 10 of the esophageal LMs were incidentally detected (mean size 0.5 cm), the other 20 were non-incidental (mean size 3.4 cm). ICC were identified in all esophageal LMs and constituted an average of 20% of the neoplastic cells. Focally, these cells constituted upto >50% of the lesional cells. The density of these cells was significantly higher than the background muscularis propria. Hyperplasia of ICC was not identified in the adjacent muscle. ICC were identified in 5 of 7 gastric LMs and they constituted an average of 5% of the neoplastic cells. ICC were identified in 1 of 3 small bowel LMs and were entirely absent in all superficial colonic LMs.
Conclusions: ICC are universally present in deep esophageal LMs, and may be mistaken for GISTs, particularly on biopsy samples, an error associated with adverse clinical consequence. ICC are also identified in gastric and intestinal LMs, albeit in a smaller proportion of cases. Intralesional ICC could either represent hyperplastic ICC colonizing LM; alternatively, these LMs may represent a hamartomatous process.
Category: Gastrointestinal

Monday, March 4, 2013 1:00 PM

Poster Session II # 119, Monday Afternoon

 

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