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DOI: 10.1055/s-0031-1291602
Osseous metaplasia of the colon in an ulcerative proctosigmoiditis
Publication History
Publication Date:
06 March 2012 (online)
A 77-year-old woman presented with acute abdominal pain and hematochezia. The patient reported a normal routine colonoscopy 2 years ago. Her long-term medication consisted of statins, allopurinol, and triazolam. Additionally she had a short-term analgesic medication (naproxen). At colonoscopy, a marginal macroscopic inflammation of the sigmoid colon and a 4-mm rectal polypoid lesion were visible ([Fig. 1]).
During histological examination, a mixed inflammatory infiltrate was visible in the lamina propria, with multiple crypt abscesses ([Fig. 2]). The polypoid lesion showed hyperplastic crypts and foci of heterotopic bone formation ([Fig. 3]). Small regions with surface ulceration could be seen. Thus the histopathological diagnosis was ulcerative proctosigmoiditis with metaplastic bone formation. It seems that the bone formation had persisted for a long time and that the finding of ulcerative colitis was overlaid by an infectious component. Due to a normal number of leukocytes in the blood sample, and unremarkable stool samples, a parasitic infection was excluded.
Heterotopic ossification in the gastrointestinal tract is described predominantly in mucin-producing carcinomas of the colon [1]. Descriptions of ossification within inflammatory gastrointestinal lesions are extremely rare, and the pathological mechanisms remain unclear. Sperling et al. assumed that bone-forming osteoblasts differentiate from immature fibroblasts [2]. Rifas et al. demonstrated that T-cell cytokines regulate the differentiation process of human mesenchymal stromal cells into osteoblasts by inducing bone morphogenetic protein-2 (BMP-2) [3]. Yu et al. reported that an active actin receptor-like kinase-2 (ALK2), activated by BMP receptor 1, leads to ectopic bone formation [4]. Finally, Shafritz et al. showed that overexpression of BMP-4 in lymphocytes is associated with ectopic osteogenesis in fibrodysplasia ossificans progressiva [5]. Overall, chronic inflammatory processes seem to play an important role in ectopic bone formation.
Endoscopy_UCTN_Code_CCL_1AD_2AJ
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References
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- 4 Yu PB, Deng DY, Lai CS et al. BMP type I receptor inhibition reduces heterotopic ossification. Nat Med 2008; 14: 1363-1369
- 5 Shafritz AB, Shore EM, Gannon FH et al. Overexpression of an osteogenic morphogen in fibrodysplasia ossificans progressiva. N Engl J Med 1996; 335: 555-561