Anatomical Pathology Interesting Case Conference

Microscopic Description:

Histology reveals small, round, scattered blue malignant cells infiltrating the bladder lining.

Surrounded by myxoid matrix.

Immunohistochemistry was positive for Myogenin.

Discussion:

Bladder rhabdomyosarcoma is a rare, malignant soft-tissue tumor arising from primitive muscle cells. It can be Embryonal (Botryoid or spindle cell), alveolar or rhabdomyosarcoma.

Affects predominately children between 2-6 years (mostly embryonal). Has association with Wilms tumor and Dandy-Walker syndrome.

Bladder is the most common site affected followed by vagina, vulva and nasal cavity. These tumors are often painless and present with intermittent gross hematuria.

Grossly, The tumor is a polypoid mass arising mostly from the trigone into the bladder lumen. The botryoid variant has a typical grape-like exophytic appearance.

Microscopically, there is a loose myxoid stroma, and a layer of tumor cells beneath the uroepithelial lining known as the Cambium layer. The tumor cells appear small, blue, round, with  moderate to abundant eosinophilic fibrillar cytoplasm with intracytoplasmic cross-striations, oval to elongate nuclei containing finely to coarsely stippled chromatin, and small indistinct nucleoli.

IHC= Myogenin +, MyoD1 +

It is managed by combination of surgical resection and adjuvant chemotherapy. Recurrence in seen when inadequately excised. Low stage exophytic pattern has a 10-year survival of 91% and. intramural endophytic growth pattern has 68% favorable prognosis.

Patients receiving chemotherapy and tumor resection have OS =83.6 ± 7.5%, preoperative radiochemotherapy followed by tumor resection have OS =87.8 ± 8.1% and those with incomplete tumor resection and radiochemotherapy postoperatively have OS =39.9 ± 14.8%.

References:

Paner GP, McKenney JK, Epstein JI, Amin MB. Rhabdomyosarcoma of the urinary bladder in adults: predilection for alveolar morphology with anaplasia and significant morphologic overlap with small cell carcinoma. Am J Surg Pathol. 2008 Jul;32(7):1022-8.

 

Martin-Giacalone BA, Weinstein PA, Plon SE, Lupo PJ. Pediatric Rhabdomyosarcoma: Epidemiology and Genetic Susceptibility. J Clin Med. 2021 May 9;10(9):2028.

Chen, K. W., Wu, F. M. W., Lee, V. K. M., & Esuvaranathan, K. (2015). Embryonal Rhabdomyosarcoma of the Adult Urinary Bladder: A Rare Case Report of Misclassification as Inflammatory Myofibroblastic Tumor. Case Reports in Surgery, 2015, 1–4. https://doi.org/10.1155/2015/510508

Ahsaini, M., Ouattar, K., Azelmad, H., Mellas, S., Ammari, J. E., Tazi, M. F., Fassi, M. J., Farih, M. H., Sekal, S., & Harmouch, T. (2018). A rare pure embryonal rhabdomyosarcoma of the urinary bladder in an adult successfully managed with neoadjuvant chemotherapy and surgery: a case report. Journal of Medical Case Reports, 12(1). https://doi.org/10.1186/s13256-018-1870-1

Seitz G, Dantonello TM, Int-Veen C, Blumenstock G, Godzinski J, Klingebiel T, Schuck A, Leuschner I, Koscielniak E, Fuchs J; CWS-96 Study Group. Treatment efficiency, outcome and surgical treatment problems in patients suffering from localized embryonal bladder/prostate rhabdomyosarcoma: a report from the Cooperative Soft Tissue Sarcoma trial CWS-96. Pediatr Blood Cancer. 2011 May;56(5):718-24. doi: 10.1002/pbc.22950.

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