vascular neoplasms are the most common primary nonlymphoid , nonhematopoietic neoplasms of the spleen , including hemangioma , lymphangioma , hamartoma , littoral cell angioma , angioendothelioma , and angiosarcoma . there are different types of splenic angioendothelioma such as kaposiform angioendothelioma , myoid angioendothelioma ( mae ) and epithelioid angioendothelioma . the age of presentation , pathologic findings , and clinical behavior are different in these types of ae . in this report , we will describe our experience with a rare case of splenic mae ( with the patient s permission and consent ) . a 38-year - old woman presented with epigastric abdominal pain and fullness since several months . a computed tomography ( ct ) scan revealed a mass in the splenic parenchyma measuring 33 cm ( figure 1 ) . fine - needle aspiration cytology of the mass was inconclusive and showed very few small clusters of spindle cells , reported as unsatisfactory . tru - cut biopsy showed a hypervascular tumor with tiny and small vascular channels with no significant atypia or mitosis . immunohistochemistry ( ihc ) was performed which showed reactive tumors cells with endothelial markers such as cd31 and cd34 , nonreactive for cd45 , and cytokeratin . proliferative index by ki67 was very low ( less than 1 per 10 hpf ) . therefore , with the diagnosis of splenic vascular tumor , most probably ae , the patient underwent splenectomy . ct scan of the abdomen shows a 3 cm splenic mass ( note congenital absence of the left kidney ) . moreover , serial cut sections showed a well - defined round , pinkish and spongy mass measuring 333 cm ( figure 2 ) . histologically , the same as tru - cut biopsy , the lesions showed a well - defined mesenchymal tumor mainly composed of spindle to histiocytic tumoral cells , which formed small capillary - like vascular channels . these tumor cells were embedded in eosinophilic stroma rich in spindle to plump stroma cells . tumor cells were reactive for cd31 ( figure 3a ) , with low mib-1 index and negative leukocyte common antigen ( lca ) . the stromal cells were reactive with smooth muscle actin ( sma ) ( figure 3b ) . there was little nuclear atypia and the mitotic rate was low ( about 1/10 high - power field ) . a ) high power view of the tumor cells show monomorphic cells creating different sized vascular channels accompanied with stromal cells . b ) sections from immunohistochemistry of the tumor show reactivity of the stromal cells with sma . the inset shows positive cd31 . according to the histological and immunohistochemical findings , diagnosis of mae because of the small size of the tumor , complete excision was performed without any further medical treatment . the patient had an uneventful postoperative period and she was discharged in a good general condition . the spleen is composed of two compartments , namely red pulp and white pulp . most of the splenic tumors originate from white pulp ( i.e. lymphohematopietic tumors ) . the second most common tumors of the spleen are vascular tumors originated from red pulp . angioendothelioma is a vascular tumor with morphologic appearance and a clinical course intermediate between hemangioma and angiosarcoma . however , this tumor can also be seen in the liver , lung and other visceral organs , but the behavior and clinical characteristics of the tumor in these two locations are completely different . splenic angioendothelioma has a wide range of morphologic and biologic behavior , composed of kaposiform , myoid and epithelioid angioendothelioma . among these types , mae is the least common and 6 cases have been reported in the english literature so far . table 1 shows the clinicopathologic and radiologic findings in these three cases . a comparison of the clinical characteristics of the reported 6 cases and the current case of myoid angioendothelioma of the spleen the age of presentation was from 3 to 46 years with female to male ratio of 4/3 , including our case . most of the previous cases were detected incidentally during investigation for other underlying diseases and only one case was found secondary to patient s evaluation for the cause of abdominal pain and discomfort . imaging in mae of the spleen can be very helpful , but in contrast to hemangioma , it is hypoechoic in ultrasonography ( us ) with clear demarcation . the lesions classically show a range of morphologic features with epithelioid to spindle - shaped tumoral cells forming small vascular channels , mild atypia , low mitotic figures , and lack of necrosis . this tumor displays intermediate biologic behavior , although until now the number of cases has been too low to make a definite evaluation of the prognosis and survival of patients with mae . splenic mae is such a rare tumor that , to the best of our knowledge , only 6 cases are reported in the english literature . these tumors , as in our case , are mainly composed of spindle and epithelioid tumoral cells and the endothelial nature of cells has been confirmed by characteristic immunoreactivity for cd31 , cd34 , and factor viii - related antigen . intervascular stroma contains bland intermediate sized polygonal to spindle cells with little atypia and low mitosis , and these cells show strong reactivity for sma and actin , but negative for endothelial markers . our case showed no reactivity for sma in tumoral cells and most of the cells were reactive for endothelial markers , and stromal cells were strongly reactive with sma . definitive diagnosis of mae is based on morphological and immunohistochemical findings that differentiate it from other vascular lesions of the spleen , including splenic hemangioma , lymphangioma , angiosarcoma , littoral cell angioma , hamartoma , and sclerosing angiomatoid nodular transformation ( sant ) of the spleen . splenic hemangioma is the most common primary tumor of the spleen , often of cavernous variety . grossly appear as circumscribed , nonencapsulated , honeycomb - like mass and histologically consisting of large interconnected blood - filled spaces lined by a monolayer of bland looking endothelial cells that differentiate it from mae . splenic lymphangioma is composed of thin - walled cystic structures of varying size lined by flat , bland - looking endothelium and filled with pink proteinaceous material devoid of red blood cells . littoral cell angioma is a unique lesion to the spleen . grossly , the tumor is multiple , nodular , and dark - red with spongy cystic appearance . microscopically , it is characterized by anastomosing and cyst - like vascular channels with papillary projections lined by sloughed plump endothelial cells often showing hemophagocytosis . the tumor cells demonstrate dual expression of endothelial and histiocytic markers that differentiate it from other vascular tumors . the immune phenotype has been established to be cd68/cd31/lysosyme / vwf / cd21/cd34/cd8 , which is indicative of dual derivation of the neoplasm . the characteristic morphology includes anastomosing and cyst - like vascular channels with papillary projections lined by sloughed plump endothelial cells and immunoreactivity for cd68 . histologically , there are anastomosing networks of blood vessels with highly atypical spindled cells that show enlarged , irregular hyperchromatic nuclei . splenic hamartoma is the term used for a nodular lesion of the spleen , composed of unorganized vascular channels of varying width , with intervening red pulp - like disorganized stroma with or without lymphoid follicles . although rendering a diagnosis can be difficult , endothelial cells that are positive for cd8 are a key feature that differentiates hamartoma from other vascular lesions of the spleen . microscopically , it consists of multiple well - circumscribed vascular nodules showing plump endothelial cell and extravasated erythrocytes . the nodules are encircled by a variable lymphoplasmacytic infiltrate , spindle cells , and collagenous stroma . the vascular nodules display a complex mixture of endothelial phenotypes resembling splenic sinusoids ( cd34/cd31/cd8 ) , capillaries ( cd34/cd31/cd8 ) , and small veins ( cd34/cd31/cd8 ) . it has been supposed that sant represents an especial hamartomatous transformation of splenic red pulp in response to an exaggerated nonneoplastic stromal proliferation . the nodular pattern of growth , presence of collagenous stroma between the nodules , and presence of three distinct types of vessels according to immunostaining can differentiate it from other splenic vascular tumors . epithelioid hemangioendothelioma of the spleen is very similar to its liver counterpart ( i.e. composed of epithelioid cells creating small vascular channels and with no myoid sma positive stromal cells ) . another angioendothelioma in the spleen is kaposiform angioendothelioma ; consist of irregular and infiltrating nodules of densely packed spindle - shaped tumor cells with small slit - like blood vessels , which were separated with hyalinized hypocellular fibrous stroma . they are almost exclusively seen in pediatric age group and are extremely rare in adults . it means that vascular channels are very similar to kaposi sarcoma ( i.e. slit - like ) . the therapeutic strategies for splenic myoid angioendothelioma have been limited and the only effective therapy is complete splenectomy . although the amount of literature regarding this tumor is very low , however , it seems that complete excision is a complete cure for this type of angioendothelioma .
most common tumors of the spleen are hematologic and lymphoid malignancies . 
 non - lymphoid and non - hematologic tumors of the spleen are very rare , the most common of which are vascular tumors . 
 this group of tumors in the spleen is composed of heterogeneous tumors such as hemangioma , angioendothelioma ( ae ) , littoral cell angioma , and angiosarcoma . there are several histologic forms of ae such as epithelioid ae , kaposiform ae , and myoid ae . among these splenic vascular tumors , 
 myoid angioendothelioma ( mae ) seems to be the least common type . 
 it is a distinct tumor ; composed of endothelium - derived tumor cells and a special type of stromal tumor cells that seems to have borderline low - grade malignant potential . 
 herein , we report our experience with a young woman presented with chronic abdominal pain and splenic mass that turned out to be myoid ae of spleen with an uneventful surgery and excellent recovery period . to the best of our knowledge , 
 such an occurrence is very rare in the spleen .