From the Archives of the AFIP: Genitourinary Rhabdomyosarcoma in Children

Radiologic-Pathologic Correlation

Abstract Introduction Clinical Features

Pathologic Features Radiologic Features Differential Diagnosis Treatment and Prognosis

Summary Source Information References

Differential Diagnosis

The imaging features of genitourinary rhabdomyosarcoma are typically nonspecific. A rational approach to differential diagnosis must incorporate the anatomic site of the lesion with the patient's age, clinical and laboratory data, and evidence of local spread or metastatic disease.

Benign mural masses of the urinary bladder such as polyps and hemangiomas are difficult to distinguish from rhabdomyosarcoma and may require biopsy for definitive diagnosis. Ectopic ureteroceles are congenital abnormalities characterized by submucosal dilatation of the distal ureter, producing an intraluminal bladder mass that may, particularly if it is large, be mistaken for a neoplasm. In a child with a history of urinary tract infection, sonographic depiction of a cystic bladder mass and an obstructed upper pole of a duplicated renal collecting system usually leads to the correct diagnosis.

Rarely, cystitis may mimic rhabdomyosarcoma of the urinary bladder. The terms pseudotumoral cystitis, cystitis cystica, cystitis follicularis, cystitis glandularis, and bullous cystitis have been used to describe benign, masslike, nonspecific inflammatory changes of the urinary bladder wall (38,39). Edema of the lamina propria, proliferation of transitional epithelium, and proliferation of mucosal or submucosal mucus glands produce cystlike mucosal elevations, which may simulate a polypoid neoplasm on contrast-enhanced images of the bladder (Figure 17). Rosenberg and colleagues (39) reviewed the clinical and radiologic reports for 17 children (aged 13 months to 13 years) with cystitis, in whom rhabdomyosarcoma of the urinary bladder was suspected initially, and correlated the findings with available cystoscopic and biopsy results. The authors concluded that inflammation rather than neoplasm should be strongly considered when typical clinical findings of lower urinary tract infection (hematuria, dysuria, frequency) are correlated with cystographic and sonographic demonstration of reduced bladder capacity; circumferential mural thickening; intact mucosa; bullous lesions; and isoechoic focal, multifocal, or circumferential thickening of the bladder wall. They also recommended that repeat imaging be performed 2 weeks after treatment with antibiotics. Normal results from sonography or cystography at that time permit confident distinction of inflammation from neoplasm and obviate biopsy (39).

Paratesticular masses in children include hydroceles, masslike swelling due to epididymitis, and neoplasms such as yolk sac tumor. Hydrocele is readily diagnosed with sonography. However, paratesticular rhabdomyosarcoma may be mistaken for epididymitis, because both may appear as a hyperemic mass with abnormally high diastolic flow at Doppler evaluation (Figure 7) (34,35). Similarly, the finding of increased blood flow to the scrotum at scintigraphy (Figure 7) may erroneously suggest inflammation instead of neoplasm.

The differential diagnosis of vaginal rhabdomyosarcoma includes polyps, urethral prolapse, hydrometrocolpos, and neoplasms such as yolk sac tumor.

In rare cases in which children present with bone metastases from rhabdomyosarcoma but the primary site remains unknown, the radiologic findings of multiple lytic lesions invoke a differential diagnosis that includes neuroblastoma, leukemia, Ewing sarcoma, and lymphoma. In these cases, appropriate immunohistochemical markers should be sought in the biopsy specimen to establish the correct diagno- sis (16).

Abstract Introduction Clinical Features

Pathologic Features Radiologic Features Differential Diagnosis Treatment and Prognosis

Summary Source Information References