Myoid Angioendothelioma: A Rare Benign Splenic Tumor

A 54-year-old female was referred to our clinic for evaluation of an incidentally found splenic mass revealed during a routine abdominal ultrasound examination. The patient denied any abdominal trauma, complaints, or past surgical operations. His medical history was unremarkable. Baseline hematological and biochemical investigations as well as the tumor markers were all within the normal ranges. Magnetic resonance imaging demonstrated a hyperintense splenic lesion, of a total size of 5 cm, which corresponded to the splenic tumor. As the nature of the splenic mass could not be precisely determined by preoperative assessments nor malignancy could be excluded, we opted for laparoscopic splenectomy. The surgery was completed without complications and the postoperative course was entirely uneventful. The patient was discharged from the clinic 4 days later. Written informed consent was obtained from the patient.

Twenty-one years after the first case of MAE was reported by Kraus and Dehner (1999), the small number of published papers makes it difficult to draw conclusions about this rare splenic entity.¹ In most cases, MAE is clinically silent, but mild abdominal discomfort may occur.² It is usually found by coincidence as an incidental finding during imaging diagnostics due to some other medical condition. Despite the use of modern radiological imaging, radiological findings, which could help to unequivocally diagnose MAE, have not been defined so far. Primary neoplasms of the spleen, such as haemangioma, hamartoma, angiosarcoma, haemangiopericytoma, and haemangioendothelioma or metastatic disease, are common differentials.³ Some authors consider fine needle aspiration biopsy as a useful procedure to define the nature of splenic neoplasms, but apart from the possible splenic rupture and bleeding, the specimens in most cases may not be reliable.^4,5

Myoid angioendothelioma of the spleen has an indolent course with a favorable prognosis. Disease recurrence has not been reported. Given that preoperative diagnostics is inconclusive, splenectomy, followed by histological and immunohistochemical analysis, is required to confirm the diagnosis.

FIG. 1.

A-D.Histomorphology with mesenchymal features (A-D): A)Histological presentation of vascular tumor with characteristic compact proliferation of vascular and stromal elements (H&,Ex100), B) Sieve-like and focally dilated vessels, (H&Ex200), C)Strong immunoexpression for CD34, (IHCx100), D) Immunopositivity for Smooth muscle actin in stromal cells, (IHCx100).