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7 April 2005 - Case of the Week #2

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This case was contributed by Dr. Celso Rubens Vieira e Silva, Hospital Aliança, Salvador, Bahia, Brazil, who we thank for contributing to the education of pathologists worldwide.

Case of the Week #2

Clinical history:
A 53 year old woman underwent laparotomy for a benign pancreatic cyst and an enlarged spleen was noted. It weighed 425 grams and measured 15 x 9 x 7 cm. A splenectomy was performed.

The spleen had an unencapsulated but well circumscribed, 6.0 cm tumor and was otherwise unremarkable.

Gross images:

Spleen with well circumscribed, dark red tumor

Close up of tumor

Microscopic description:
The tumor was composed exclusively of red pulp elements. No follicles or trabeculae were present.

What is your diagnosis?

Click here for diagnosis and discussion:

Diagnosis: Splenic hamartoma

Splenic hamartoma, also called splenoma or splenadenoma, is rare, representing 0.2% or less of splenic surgical specimens. It occurs in patients of any age, with no gender preference. It is frequently an incidental finding of imaging studies, at surgery or at autopsy but may also be associated with symptoms of hypersplenism, including thrombocytopenia. It has a benign clinical course.

Grossly, it is a large, well circumscribed but unencapsulated, dark red, nodular lesion, often with hemorrhage. It is composed almost exclusively of red pulp elements, and may have foci of extramedullary hematopoiesis but there are no white pulp elements (i.e., no follicles or trabeculae). The red pulp elements include sinusoids lined by littoral cells with a unique phenotype (CD8+, CD31+, CD34-), capillaries lined by usual type endothelium (CD8-, CD31+, CD34+) and small veins (CD8-, CD31+, CD34-). The red pulp also contains histiocytes, antigen presenting cells, fibroblasts and pericytes. Occasional cases may have scattered large, bizarre stromal cells, that appears to represent a degenerative and not a neoplastic change (AJSP 2005;29:109)

The differential diagnosis of splenic hamartoma includes hemangioma, which may be morphologically similar but is CD8 negative, unlike the CD8 positive littoral cells which are one of the components present in splenic hamartoma.

Additional references: Arch Pathol Lab Med 2001;125:1483

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