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

Introduction

Rhabdomyosarcoma is a relatively common solid neoplasm of unknown cause that may arise from a primitive cell in any organ system. Although the term rhabdomyosarcoma connotes a mesenchymal tumor derived from striated muscle, rhabdomyosarcoma typically arises in sites lacking striated muscle. Rhabdomyosarcoma represents 5% 10% of malignant solid tumors of childhood, ranking fourth in frequency after central nervous system neoplasms, neuroblastoma, and Wilms tumor. On the basis of the annual incidences of 4.5 cases per 1 million white children and 1.3 cases per 1 million black children, there are approximately 250 new cases of rhabdomyosarcoma in the United States each year (1).

Genitourinary rhabdomyosarcomas include tumors originating in the urinary bladder, prostate, testes and paratesticular sites, penis, perineum, vagina, and uterus. The large size and infiltrative growth pattern of intrascrotal rhabdomyosarcoma may make the exact site of origin difficult to determine (2). As a result, the term paratesticular rhabdomyosarcoma has been applied to primary tumors arising in the spermatic cord, testis, penis, and epididymis. Similarly, the term bladder-prostate rhabdomyosarcoma is used to describe rhabdomyosarcoma originating in the urinary bladder or prostate because the tumor often infiltrates both structures. Genitourinary rhabdomyosarcoma accounts for 15% 30% of rhabdomyosarcoma cases in children, is second in frequency to rhabdomyosarcoma of the head and neck (3,5), and is the most common tumor of the lower genitourinary tract in children during their first 2 decades of life (6).

The natural history of childhood rhabdomyosarcoma varies with the anatomic site of the lesion (7). Thus, from a practical standpoint, genitourinary rhabdomyosarcoma may be regarded as a unique disease, differing in its clinical characteristics, pattern of metastatic spread, treatment, and prognosis from rhabdomyosarcoma occurring elsewhere in the body. Moreover, the clinical approach to the patient with rhabdomyosarcoma differs depending on the anatomic subtype of the tumor, that is, whether it is a paratesticular, bladder and bladder-prostate, or gynecologic lesion.

This article, illustrated with cases contained in the radiologic pathology archives of the Armed Forces Institute of Pathology, examines the clinical, pathologic, and radiologic features of genitourinary rhabdomyosarcoma in children and discusses differential diagnosis, treatment, and prognosis based on anatomic subtype.

Abstract Introduction Clinical Features

Pathologic Features Radiologic Features Differential Diagnosis Treatment and Prognosis

Summary Source Information References