Sclerosing Extramedullary Hematopoietic Tumor (SEHT) Mimicking a Malignant Bile Duct Tumor-Case Report and Literature Review

Abstract

Introduction: Sclerosing Extramedullary Hematopoietic Tumor (SEHT) is a very rare lesion associated with chronic myeloproliferative disorders (CMPD). SEHT can mimic morphologically, both macroscopically and microscopically, a wide variety of tumors/lesions. Case presentation: We present the case of a female patient diagnosed with gallstones for which surgery was decided. Intraoperatively, a malignant tumor of extrahepatic bile ducts was suspected. A frozen section examination raised the suspicion of a mesenchymal tumor or an inflammatory pseudotumor. The histological evaluation of the permanent sections, supplemented with an immunohistochemical investigation (IHC), was the one that established the diagnosis of SEHT, based on the presence of areas of sclerosis, atypical CD31+ megakaryocytes, myeloid and erythroid elements. Conclusions: The authors present the difficulties of a morphological diagnosis on the frozen section and on permanent sections in the absence of relevant clinical information and make a review of the literature data dedicated to the subject.

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

“…SEMHT may occur at various sites, including the thyroid gland, lung, lymph nodes, gastrointestinal tract, kidney, skin and breast (7). The clinical symptoms depend on the location of the SEMHT and mainly include abdominal pain, headache, appearance of a skin mass and lacrimal gland swelling (2,(8)(9)(10). At present, few cases of SEMHT have been reported, and the majority of SEMHT cases have a history of myelofibrosis.…”

“…In terms of gross pathology, SEMHT appears rubbery, pink, white or yellowish-brown with clear boundaries. SEMHT can be sometimes lobulated and has the ability to infiltrate the surrounding tissues ( 8 ).…”

“…Histopathologically, SEMHT is characterized by atypical megakaryocytes, erythrocytes and granulocyte precursors distributed in the sclerotic or fibromyxoid stroma ( 2 ). SEMHT can also include adipose tissue trapped within the tumor ( 8 ). Usually, the fibrous stroma is dominant; therefore, it is challenging to identify the hematopoietic components in conventional hematoxylin and eosin-stained sections.…”

“…In this context, megakaryocytes are scattered throughout the matrix and may appear alone or in clusters ( 12 ). Atypical megakaryocytes are characterized by hyperchromatic, multilobulated, giant, ink-blot-like nuclei with a slightly eosinophilic cytoplasm ( 8 ). In addition to the enlarged atypical megakaryocytes, loose aggregates of immature granulocyte precursors and scattered erythroid precursor cells are present, which are most apparent near to blood vessels ( 9 ).…”

“…Atypical megakaryocytes stain positively for CD61, CD41, CD31 and factor VIII. Granulocytes stain positively for MPO, and erythrocyte precursors stain positively for glycoprotein A and hemoglobin ( 8 ). CD163 staining reveals the accompanying histiocytes rather than the expanded megakaryocyte forms.…”