Littoral Cell Angioma
General: Thought to arise from "littoral cells" found in splenic red pulp sinuses which normally have features intermediate between those of endothelial cells and macrophages (the cell of origin is under debate due to the relatively recent finding that normal littoral cells are CD34+ but littoral cell angiomas are typically CD34-).
Mean age at presentation is 49 y.o., with a wide range. Typically there is splenomegaly with thrombocytopenia and anemia. They are generally benign in behavior, but there is an association with colon cancer, pancreatic cancer, renal carcinoma, and meningioma.
The most important differentials are:
Gross: Usually multiple well to moderately defined congested/hemorrhagic red to black unencapsulated nodules, sometimes large, within an enlarged spleen. Tiny cystic spaces may be seen within the nodules.
Microscopic: Anastomosing vascular channels lined by tall or flat endothelial cells which may anastomose with normal splenic sinuses at the periphery. May have a psuedopapillary aspect or may appear as dilated cavernous vascular spaces. Plump exfoliated cells are often found within the vascular channel lumen. Foci of extramedullary hematopoiesis, hemosiderin pigment, and/or calcification may be present.
Lacks cellular atypia, mitoses, or invasion of surrounding organs, which are features of angiosarcoma.
Staining:
- Positive: Factor VIII-related antigen+, CD68+, Lysozyme+
- Negative:
- Suggested panel:
(1, 2)
Images:
Cases: