Epitheloid hemangioendothelioma of urinary bladder

Epitheloid hemangioendothelioma is an uncommon vascular neoplasm and has an unpredictable clinical behavior. It is characterized by round or spindle-shaped endothelial cells with cytoplasmic vacuolation. Most often, epitheloid hemangioendothelioma arise from the soft tissues of the upper and lower extremities and it has borderline malignant potential. We describe the (cid:222) rst reported case of epitheloid hemangioendothelioma in the urinary bladder, which was treated by transurethral resection. The diagnosis was con (cid:222) rmed by immunohistochemistry.


INTRODUCTION
Vascular tumors are uncommon and show a wide clinicopathological variation ranging from benign to borderline malignant to complete malignant lesions. Epitheloid vascular neoplasms are a rare group of tumors characterized morphologically by the presence of epitheloid endothelial cells. Vascular tumors composed of these cells are further divided into three distinct varieties: epitheloid hemangioma, epitheloid hemangioendothelioma (EHE), and epitheloid angiosarcoma. [1] Hemangioendotheliomas are vascular tumors of low-malignant potential with a behavior intermediate between hemangioma and conventional angiosarcoma. [1] Epitheloid hemangioendothelioma is an uncommon vascular neoplasm and has an unpredictable clinical behavior.
Vascular tumors like cavernous hemangiomas and few cases of angiosarcoma have been reported to occur in the urinary bladder. [2] However, to the best of our knowledge, till date there is no documentation of the occurrence of EHE in the urinary bladder. We describe the Þ rst case of EHE of the urinary bladder which was confirmed by immunohistochemistry (IHC).

CASE REPORT
A 17-year-old male patient presented with history of episodic painless hematuria of 7-year duration and obstructive voiding symptoms with overß ow incontinence for 2 years. There was no history of any bowel symptoms or neurological deÞ cit in the lower half of the body. Physical examination revealed a palpable distended bladder. A Þ rm mass was palpable above the prostate on digital rectal examination.
This patient had his Þ rst episode of hematuria 7 years prior to his presentation to our hospital. At that time he was evaluated in another hospital where a computerized tomographic scan (CECT) of the abdomen was done which revealed a 2.4 × 2.5 × 2.3 cm 3 mass at the bladder base. Multiple biopsies were done at different centers and were reported as cystitis, histiocytic neoplasm, inß ammatory myoÞ broblastic tumor, and rhabdomyosarcoma. The IHC was not done at any point of time for pathological diagnosis. The patient never received deÞ nitive treatment before presenting to us with the above-mentioned complaints.
This patient had normal renal parameters (blood urea and serum creatinine) at presentation. Urine cytology was negative for malignant cells. Owing to incontinence and bilateral hydroureteronephrosis (HDUN), per urethral catheterization was done and subsequently imaging studies were performed. Ultrasound (U/S) of the abdomen revealed 4 × 4.3 × 4.3 cm 3 mass in the trigone with a thickened urinary bladder and bilateral HDUN. Micturition cystourethrogram revealed elongated diverticulated bladder (mimicking neurogenic bladder) with no vesicoureteric reflux and high-postvoid residual urine (PVR). Magnetic resonance imaging of the spine was normal. The CECT of the abdomen revealed a 4-cm solid enhancing mass over the base of the bladder with no perivesical extension or lymphadenopathy [ Figure 1]. Cystoscopy revealed a solid polypoidal mass over the trigone with an incomplete calciÞ ed rim and a normal prostate. A transurethral complete resection of the tumor

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was done and deep biopsies were taken. Tumor was highly vascular and bleeding during resection. The patient had uneventful postoperative course and voided normally with insigniÞ cant PVR after the catheter was removed.
Pathological examination revealed polygonal to spindleshaped tumor cells with abundant eosinophilic cytoplasm and at places showing intracellular vacuolization [ Figure 2]. Mucin staining with Alcian blue-Periodic acid Schiff (PAS) was negative excluding the possibility of mucin in the intracytoplasmic vesicle. There was marked nuclear pleomorphism and prominent nucleoli and occasional mitoses were identiÞ ed. The IHC for desmin, CD-34, CD-68, S-100, epithelial membrane antigen (EMA), chromogranin, and cytokeratin were negative but positive for endothelial cell markers CD-31 [ Figure 3] and Factor VIII. The overall features were suggestive of epitheloid hemangioendothelioma. At 1-year follow-up, the patient was asymptomatic and ultrasound showed no recurrence in the bladder, no HDUN, and an insigniÞ cant PVR. Cystoscopy showed no tumor recurrence in the bladder.

DISCUSSION
The EHE was Þ rst described by Weiss and Enzinger in 1982 as a borderline or low-grade neoplasm. [3] Owing to overlapping histological features, these tumors are considered a spectrum of lesions, where EHE is believed to be in the middle of the spectrum with a behavior intermediate between epitheloid hemangioma and epitheloid angiosarcoma. While EHE occurs most commonly in the soft tissue of the extremeties, visceral involvement (bone, liver, spleen, lung, etc.) has also been reported. In the present case, the young age of the patient, the absence of any conditions that might predispose to transitionalcell carcinoma, as well as the fact that the tumor has not progressed signiÞ cantly over 7 years despite not offering deÞ nitive treatment has made us believe that the tumor could be a benign non-urothelial tumor.
The differential diagnoses that were considered based on the pathological Þ ndings are shown in Table 1. Characteristic histopathologic features of EHE include: plump cells with eosinophilic hyaline cytoplasm, angiocentric location, cytoplasmic vacuoles representing primitive vascular lumina, cells arranged in cords, a chondromyxoid matrix, and papillary tufts of plump cells within lymphovascular spaces. [1] ConÞ rmatory evidence is described as erythrocytes within cytoplasmic vacuoles or primitive tumor-cell lined channels which mirrors the primitive vasoformative character of EHE and immunohistochemical evidence of endothelial differentiation. [1] It has been widely accepted