An Adult Paratesticular Malignant Ectomesenchymoma With Post-operative Flare-up of Lung Metastasis.

Malignant ectomesenchymoma (MEM) which is derived from the remnants of migratory neural crest cells (ectomesenchyme) is a rare and rapidly progressing tumor consisting of neuroectodermal and mesenchymal neoplastic elements. This tumor occurs mostly in children and adolescents, but rarely in adults. We report a 34-year-old male with left paratesticular malignant ectomesenchymoma who received radical orchiectomy and was followed by post-operative flare-up of lung metastasis within 2 weeks. We present the overall treatment strategies for this extremely rare tumor and related findings.