Sclerosing extramedullary hematopoietic tumor of the colon: A case report and literature review.

Sclerosing extramedullary hematopoietic tumor (SEMHT) is a rare tumor that can occur in association with some chronic myeloproliferative neoplasms, particularly myelofibrosis. The morphology of SEMHT can mimic that of a wide variety of other lesions, both macroscopically and microscopically. SEMHT originating from the colon is extremely rare. The present study reports a case of SEMHT in the colon with involvement of the peri-intestinal lymph nodes. On the basis of the clinical symptoms and endoscopic results, a malignant tumor of colon was suspected. Pathological examination revealed the deposition of collagen and hematopoietic components in the fibrous mucus background. Immunohistochemical staining for CD61 confirmed the presence of atypical megakaryocytes, while immunohistochemical staining for myeloperoxidase and glycophorin A highlighted the existence of granulocyte and erythrocyte precursors, respectively. These findings combined with a clinical history of myelofibrosis led to the final diagnosis of SEMHT. The presence of atypical megakaryocytes with immature hematopoietic cell morphology and a good understanding of the clinical history of the patient are essential to prevent misdiagnosis. The present case emphasizes the necessity of reviewing previous hematological history and considering clinical findings together with the associated pathological results.