Abstract
Perivascular epithelioid cell neoplasms (PEComas) of the urinary bladder are extremely rare and the published cases were comprised predominantly of middle-aged patients. Herein, the authors present the first urinary bladder PEComa occurring in an adolescent. This 16-year-old Chinese girl present with a 3-year history of abdominal discomfort and a solid mass was documented in the urinary bladder by ultrasonography. Two years later, at the age of 18, the patient underwent transurethral resection of the bladder tumor. Microscopically, the tumor was composed of spindled cells mixed with epithelioid cells. Immunohistochemically, the tumor were strongly positive for HMB45, smooth muscle actin, muscle-specific actin, and H-caldesmon. Fluorescence in situ hybridization analysis revealed no evidence of EWSR1 gene rearrangement. The patient had been in a good status without evidence of recurrence 13 months after surgery. Urinary bladder PEComa is an extremely rare neoplasm and seems occur predominantly in middle-aged patients. However, this peculiar lesion can develop in pediatric population and therefore it should be rigorously distinguished from their mimickers.Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1870004378817301
Highlights
Perivascular epithelioid cell neoplasms (PEComas) are defined by the World Health Organization as “mesenchymal tumors composed of histologically and immunohistochemically distinctive perivascular epithelioid cells” [1]
Non-AML/non-LAM/non-clear cell sugar tumor of the lung (CCST) PEComas have progressively been documented in a variety of anatomical sites, such as visceral organs, soft tissue and bone [3,4,5,6,7,8,9,10]
Only 12 cases of PEComas of the urinary bladder have been documented in the Englishlanguage literature worldwide [11,12,13,14,15,16,17,18,19,20]
Summary
Perivascular epithelioid cell neoplasms (PEComas) are defined by the World Health Organization as “mesenchymal tumors composed of histologically and immunohistochemically distinctive perivascular epithelioid cells” [1]. A 2.0-cm solid mass was identified in the urinary bladder by ultrasonography. Her parents preferred to undergo regular follow-up examinations instead of mass resection despite a recommendation. At the age of 18, the girl was admitted to our hospital with 1-month history of frequent micturition without hematuria or dysuria. The patient underwent transurethral resection of the bladder tumor (TURBT). Both the intraoperative impression and a postoperative ultrasound confirmed that gross-total tumor resection had been achieved. Fluorescence in situ hybridization analysis revealed no evidence of 22q12 (EWSR1 gene) translocation, excluding the possibility of clear cell sarcoma of Figure 1 Gd-enhanced coronal T1-weighted MRI showing significantly inhomogeneously enhanced well-defined mass with a wide base. At the most recent follow-up 13 months following the surgery, the patient had been in a good status without evidence of recurrence
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