Case of the Week

2021-17/ April 26

Contributors: Alessia Cimadamore, Rodolfo Montironi

A male in his late teens, had an incidentally discovered 3 cm painless solid scrotal mass. At surgery the mass appeared to be well demarcated and adherent to the external surface of the right testis, i.e., the testis was not involved. He underwent testis-sparing “lumpectomy”.

Click on the below thumbnails to enlarge photos.

Quiz

1. What is the correct diagnosis?

a. Rhabdomyosarcoma, embryonal subtype

b. Ganglioneuroblastoma/Neuroblastoma

c. Malignant ectomesenchymoma

d. Teratoma with somatic-type malignancy

e. Gangliocytic paraganglioma

Malignant ectomesenchymoma derived from the remnants of migratory neural crest cells (i.e., ectomesenchyme), is a malignant soft tissue tumor with heterologous components (1,2,3). This tumor occurs mostly in children and adolescents (1). It can originate from the brain, face and neck, abdomen, retroperitoneal space, pelvis, perineum, scrotum, and limbs.

From the morphologic point of view, it is a biphenotypic malignant mesenchymal tumor. The component that is present in all tumors is rhabdomyosarcoma, whereas the neural component can be ganglioneuroblastoma/neuroblastoma or peripheral primitive neuroectodermal tumor (2). Immunohistochemistry has a fundamental role in the final diagnosis: the main component of the tumor cells is positive for desmin, myogenin, and myoglobin, and negative for CD34, synaptophysin, S100, SMA, EMA, and cytokeratin. The neural component, depending on its morphology, is positive for S100, NF, synaptophysin, and chromogranin A (1,2,3).

Risk-factors and outcome appear to be comparable with other highly malignant pediatric soft tissue sarcoma (2). Surgery is the mainstay of treatment.

1. Dantonello TM, Leuschner I, Vokuhl C, Gfroerer S, Schuck A, Kube S, Nathrath M, Bernbeck B, Kaatsch P, Pal N, Ljungman G, Bielack SS, Klingebiel T, Koscielniak E; CWS. Malignant ectomesenchymoma in children and adolescents: report from the Cooperative Weichteilsarkom Studiengruppe (CWS). Pediatr Blood Cancer. 2013 Feb;60(2):224-9.

2. Kao WT, Chiang YT, Tzou KY. An Adult Paratesticular Malignant Ectomesenchymoma With Post-operative Flare-up of Lung Metastasis. Urol Case Rep. 2015 Jul 15;3(5):164-6.

3. Griffin BB, Chou PM, George D, Jennings LJ, Arva NC. Malignant Ectomesenchymoma: Series Analysis of a Histologically and Genetically Heterogeneous Tumor. Int J Surg Pathol. 2018 May;26(3):200-212.

About GUPS

The Genitourinary Pathology Society (GUPS) was formed with the vision of advancing the care of patients with urologic diseases through enhancements of best practices, research, and education in the subspecialty of Urological Pathology.

GUPS is an official Companion Society of the United States and Canadian Academy of Pathology (USCAP).

Contact

gupathologysociety@gmail.com

Powered by Wild Apricot Membership Software