Splenic littoral cell haemangioendothelioma: a new low-grade variant of malignant littoral cell tumour

Aims: Littoral cell angioma is a recently described splenic vascular tumour of splenic sinus lining cells. Almost all cases of splenic littoral cell t umours hitherto described were benign. Methods and results: A splenic littoral cell tumour recurred 8 years after splenectomy, with an abdominal mass and multiple liver metastases, resultin g in the patient's death. Histologically, the original splenic tumour showe d solid areas with small necrotic foci in addition to large areas of typica l littoral cell angioma. The recurrent tumours showed increased solid archi tecture and slightly increased nuclear atypia. The tumours showed an immuno histochemical profile positive for factor VIII. CD31, CD68, cathepsin D, an d CD21 and negative for CD34 and CD8. consistent with the immunophenotype o f classic littoral cell angioma. Ki67 index in the recurrent tumours was hi gher than in the primary tumour. Conclusions: The mildly atypical. but not frankly malignant, histological f eatures as well as the protracted clinical course support definition of the tumour as 'littoral cell haemangloendothelioma'. Low rate of Ki67 staining and diploid DNA histogram with low S-phase fraction of the tumours are in accordance with a low-grade malignancy, Literature review revealed two othe r cases of littoral cell tumours with disseminated disease that may be othe r examples of littoral cell haemangioendothelioma. Littoral cell haemangioe ndothelioma should be distinguished from the overtly malignant splenic angi osarcomas, of which a few may show splenic lining cell differentiation with some immunohistochemical features of littoral cells. Due to difficulties i n predicting biological behaviour based on histological features of splenic littoral cell tumours. a long-term follow-up for these patients, especiall y for those with atypical histology, is recommended.