CASE OF THE WEEK
Editors: Francesca Khani (Frk9007@med.cornell.edu) and Mahmut Akgul (akgulm@amc.edu)
2022-05/January 31
Contributors: Natallia Sheuka, Francesca Khani
A man in his mid-50s presented with dysuria and gross hematuria.   Imaging revealed a 14.9 x 10.0 cm mass essentially replacing prostate and seminal vesicles, and invading the urinary bladder. After biopsy confirmation of malignancy, a cystoprostatectomy was performed to completely remove the tumor. On pathologic gross examination, the tumor had a fleshy, tan-white cut surface with central necrosis.
Quiz
1. What is the correct diagnosis?
a) Embryonal rhabdomyosarcoma
b) Leiomyosarcoma
c) Small cell neuroendocrine carcinoma
d) Prostatic adenocarcinoma
e) Urothelial carcinoma
1. a
Embryonal rhabdomyosarcoma
The H&E sections show a tumor composed of primitive round blue cells with scant cytoplasm and areas of spindle cells arranged in fascicles. By immunohistochemistry, the neoplastic cells showed positivity for desmin and myogenin (shown above). They also showed positivity for CD34, were weakly positive to negative for actin, and were negative for CK AE1/AE3, CAM 5.2, synaptophysin, chromogranin, TTF1, S100, GATA3, and PR immunostains (not shown). The morphologic findings and immunophenotype support the diagnosis of an embryonal rhabdomyosarcoma.
Microscopically, embryonal rhabdomyosarcomas typically show primitive undifferentiated round to spindle cells without or with only focal rhabdomyoblasts. It is important to document IHC positivity for desmin and MyoD1 or myogenin in support of the diagnosis. The differential diagnosis for this case based on the H&E appearance initially was broad, and immunohistochemistry was particularly helpful. The absence of strong positivity for actin made leiomyosarcoma less likely. A carcinoma (prostatic, urothelial, or others) should show keratin positivity, and a small cell neuroendocrine carcinoma typically would be positive for chromogranin and synaptophysin.
Embryonal rhabdomyosarcoma of the prostate in adults is an exceedingly rare and aggressive tumor, although it is the most common childhood malignancy of the prostate. Patients most often present with symptoms of dysuria or urinary obstruction and often have extensive involvement of bladder and rectum with metastatic disease at the time of initial clinical evaluation. The prognosis for adult prostatic rhabdomyosarcoma is poor.
1. Bisceglia M, Magro G, Carosi I, Cannazza V, Ben Dor D. Primary embryonal rhabdomyosarcoma of the prostate in adults: report of a case and review of the literature. Int J Surg Pathol. 2011 Dec;19(6):831-7.
2. Olivas AD, Antic T. Rhabdomyosarcoma of the Adult Prostate: A Case Report With Complete Molecular Profile. Int J Surg Pathol. 2020 Feb;28(1):92-98.
3. WHO Classification of Tumours of the Urinary System and Male Genital Organs, 4th Edition. 2016. Edited by Moch H, Humphrey PA, Ulbright TM, Reuter VE.
Natallia Sheuka & Francesca Khani
Well Cornell Medicine / New York-Presbyterian Hospital
New York, NY
Prostate
Prostate; sarcoma; embryonal rhabdomyosarcoma;