Case Report: Multifocal plexiform neurofibromas presenting as a paratesticular "string-of-beads" mass in a 7-year-old boy with neurofibromatosis type 1.

Background: Neurofibromatosis type 1 (NF1) is a common inherited tumor-predisposition syndrome with wide phenotypic variability. Plexiform neurofibromas (PNs) are characteristic NF1-associated peripheral nerve sheath tumors that may be extensive, infiltrative, and clinically silent. Genitourinary involvement is uncommon in children, and scrotal or paratesticular presentation with concomitant pelvic or retroperitoneal disease is rarely documented. Case presentation: A 7-year-old boy who met the revised clinical diagnostic criteria for NF1 presented with a 5-month history of a painless right scrotal "string-of-beads" mass. Ultrasonography showed bilaterally normal testes and multiple right inguinal extratesticular nodules continuous with an irregular paratesticular mass posterior and superior to the right testis, favoring a paratesticular/spermatic cord-adjacent process rather than a primary intratesticular tumor. Tumor markers were unremarkable. Staged CT disclosed additional multifocal lesions, including a right parietal subcutaneous lesion and a thoracic paravertebral lesion, together with substantial retroperitoneal and pelvic tumor burden partially encasing the iliac vessels without definite adjacent organ invasion. Testis-sparing scrotal exploration comprised incisional biopsy of the paratesticular lesion, excision of one superficial scrotal skin nodule, and excision of three local inguinoscrotal nodular specimens submitted as lymph-node-like tissue. Histopathology confirmed PN in the sampled paratesticular lesion and additional superficial nodular specimens; immunohistochemistry supported a benign peripheral nerve sheath tumor, with a Ki-67 labeling index of approximately 5%. Because the deep component was anatomically unresectable but not associated with pain, urinary obstruction, neurologic deficit, functional compromise, or definite adjacent organ invasion, structured surveillance was chosen rather than immediate MEK inhibitor therapy. At 6 months, the child remained clinically stable, but no interval MRI or CT had been performed. Conclusions: In a child with NF1 stigmata, an apparently superficial scrotal or paratesticular lesion may signal more extensive inguinal, pelvic, retroperitoneal, and paravertebral disease. Evaluation should extend beyond the scrotum, with MRI preferred when feasible. Management should be compartment-based: organ-preserving diagnostic surgery for accessible superficial disease, MRI-oriented surveillance for asymptomatic unresectable internal disease, and MEK inhibition for progressive, symptomatic, or function-threatening unresectable PN.