Massive diffuse intraperitoneal multicystic mass in an infant. Botryoid rhabdomyosarcoma (RMS).

An 18-month-old boy was referred for painless progressively increasing abdominal distension, poor oral intake, and lethargy since 1 year. There was no history of fever, hematurea, or intestinal obstruction. The child was pale and had a pulse rate of 150 beats/min. The child had mild respiratory distress due to huge abdominal distension. The abdomen was tense and nontender. There was no evidence of intraperitoneal free fluid or any definitive lump. The hemogram showed anemia, other blood biochemistry test results were normal. Ultrasonography of the abdomen suggested the possibility of encysted ascites. A 64-slice contrast-enhanced computed tomography of abdomen showed diffuse intraperitoneal multicystic mass, composed of variable sizes and wall thickness cysts [Figure 1]. The definitive organ of origin could not be identified. Bowel loops were displaced upward by the mass. Diagnostic laparoscopy showed a pale, soft, extremely friable mass composed of cysts of variable sizes arising from the dome of the bladder. The cysts were noncommunicating and had no fluid. The mass was loosely adhered to the bowel, liver, and peritoneum. The rest of the abdominal organs were normal. Complementary cystoscopy was performed to rule out intraluminal extension of tumor, which was normal.

Figure 1

A 64-slice contrast-enhanced computed tomography of abdomen (a) Coronal view demonstrating a multicystic mass with no fluid within the cysts occupying whole of the abdominal cavity and displacing bowels upward; (b) Bladder outline with both ureters are evident on posterior sections; and (c) Axial view suggesting a multicystic mass composed of cysts of variable sizes and wall thickness

QUESTION

Q1. What is the diagnosis?

ANSWER

Histopathology showed myxoid stroma containing undifferentiated round to spindle cells with Cambium layer of Nicholson. Furthermore, immunohistochemistry showed the tumor cells positivity for desmin, vimentin, actin, and myoglobin. So the definitive diagnosis was botryoid rhabdomyosarcoma (RMS).

Botryoid sarcoma is a variant of embryonal type RMS. It accounts for 5-10% of all RMS.[1] It is the most common malignant condition of the lower genitourinary system in infancy.[1] The lesions usually abuts an epithelial surface of hollow viscera, such as that of the bladder or vagina and projects into the lumen as a multinodular excrescences of variable sizes.[12] The median age for occurrence is 4 years. The common presentation is hematurea, frequency, urgency, and other irritative voiding symptoms or it may protrude through the urethra or vagina as a hemorrhagic, friable, grape-like mass.[12] To the best of our knowledge and search of the literature this is the first case in which the urinary bladder botryoid RMS had a huge intraperitoneal component only.

Clinicoradiological deferential diagnoses of diffuse multicystic intraperitoneal tumors in children are abdominal cystic lymphangioma, benign multicystic peritoneal mesothelioma, cystic adenomatoid tumor, pseudocyst, and immature cystic teratoma.[3]

So the botryoid sarcoma should also be considered in the differential diagnosis of intraabdominal cystic tumors (especially of pelvic origin) even if there are no urinary symptoms in the children.