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Table of Contents
Definition / general | Essential features | Terminology | Sites | Clinical features | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Electron microscopy description | Molecular / cytogenetics description | Differential diagnosisCite this page: Histiocytic sarcoma of colon. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colontumorhistiocyticsarcoma.html. Accessed July 14th, 2017.
Definition / general
- Malignant neoplasm with features of mature histiocytes
- See also topics in CNS tumor, liver tumor, lymph node - not lymphoma, spleen chapters
Essential features
- Rare primary sarcoma of the gastrointestinal tract featuring CD163 positivity
- Can be mistaken for lymphoma with infiltrating histiocytes
Terminology
- Previously also called "true histiocytic lymphoma"
Sites
- Gastrointestinal tract most common location, after skin / soft tissue
- Colonic examples are often distal (sigmoid / rectum)
Clinical features
- Median age 55 years, with no sex predilection (Am J Surg Pathol 2004;28:1133)
- Symptoms include weight loss, abdominal pain and hematochezia
- Postoperative outcome can vary from full recovery to death
Gross description
- Bulky exophytic mass with infiltrative margins
Microscopic (histologic) description
- Sheets of large epithelioid cells with abundant eosinophilic cytoplasm, oval to irregular nuclei, vesicular chromatin, prominent nucleoli and distinct borders; cells may be binucleated, giant or spindled
- Prominent inflammatory infiltrate (lymphocytes, eosinophils, neutrophils)
- Often mitotic activity and necrosis
- Regional lymph nodes generally involved
Microscopic (histologic) images
Images hosted on PathOut server:
Contributed by Dr. Raul Gonzalez, University of Rochester Medical Center (USA):
Low power
Abundant lymphocytes
High power
Multinucleated cells
Positive stains
Electron microscopy description
- Cells contain scattered lysosomes, consistent with histiocytic origin
Molecular / cytogenetics description
- May show monoclonal IgH bands or IgH and TCR gamma gene rearrangements
Differential diagnosis
- Follicular dendritic cell sarcoma: positive for CD21 and CD35
- Lymphoma: must distinguish reactive histiocytes from histiocytic neoplasm; lymphomas misdiagnosed as histiocytic sarcoma in the past were most likely to be anaplastic large cell lymphoma or diffuse large B cell lymphoma
- Myeloid sarcoma: likely to also involve blood or bone marrow, unlike histiocytic sarcoma
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