Ewing sarcoma with extensive neural differentiation: a clinicopathologic, immunohistochemical, and molecular analysis of three cases

Case Report: Primary Ewing Sarcoma of the Penis

Background

Ewing sarcoma is a malignancy that commonly affects the skeletal system and primary extraskeletal involvement is rare. Extraskeletal Ewing sarcoma (EES) arises in soft tissue anywhere in the body. These are very rarely seen aggressive tumours. There have been only 7 reported cases of EES of penis.

Case Presentation

We report a 22-year-young patient who presented to our hospital with a ulcero-proliferative growth in the shaft of penis. There were no other complaints indicating any metastasis. Incisional biopsy was suggestive of invasive malignancy. He was scheduled for a partial penectomy. Final HPE and IHC were suggestive of EES.

Conclusion

EES as a subtype of Ewing sarcoma is rare and it can occur in any soft tissue site. Hence, clinicians need to differentiate this entity from other soft tissue sarcomas. Early diagnosis and timely treatment of EES are pivotal for a favourable prognosis due to its aggressive nature.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13193-023-01793-x.

Paratesticular Ewing's sarcoma

This case report follows a 23-year-old man who presented with a painful right scrotal mass which was found to be a paratesticular vascular solid mass on ultrasound, and after uncomplicated orchiectomy, was revealed to be a high-grade extraskeletal Ewing's sarcoma. Diagnosis leading up to the orchiectomy was primarily clinical with only ultrasound used in identification and characterization of the paratesticular mass. Paratesticular masses are more commonly benign, and ultrasound is the first modality, with computed tomography and magnetic resonance imaging providing more definitive findings. We discuss imaging findings and histopathology of this rare tumor with an uncommon presentation.

Ewing Sarcoma with Ganglion Cells Post-Chemotherapy: A Case Report with Review of Literature

Karthik DhandapaniEwing sarcoma arises in both bones (most common) and soft tissues and it commonly affects young adults. The tumor is composed of small round cells showing positivity for CD99 and FLI1 on immunohistochemistry (IHC). We describe ganglion cell differentiation post-chemotherapy in Ewing sarcoma which is a rare phenomenon. A 13-year-old girl presented with a chest wall mass. On biopsy correlating with IHC, the diagnosis was rendered as Ewing sarcoma. She underwent neoadjuvant chemotherapy followed by resection of the tumor. On microscopic evaluation, the tumor showed prominent ganglionic differentiation with expression of neuronal markers. Although maturation post-chemotherapy is an established finding with better prognosis in other primitive pediatric tumors, such neural differentiation is rare with only a few case reports in Ewing sarcoma both post- and pre-chemotherapy. Clinical significance and prognosis of such differentiation which appear to be better are not yet established and needs to be elucidated.

Ewing Sarcoma Displaying Extensive Well Differentiated Neuroblastomatous Differentiation: A Case Report

INTRODUCTION

A tumor with EWSR1/FLI fusion displaying extensive well differentiated neuroblastomatous differentiation is presented.

CASE REPORT

A nine-year-old female patient had a thoracic vertebra 8 paraspinal mass. The lesion was resected incompletely. Histopathologically, a small round cell tumor with gangliomatous differentiation was seen. This was initially diagnosed as an intermixed ganglioneuroblastoma. In the completion surgery biopsy material, the small round cell component was more prominent. Immunohistochemistry for both samples showed membrane positivity for CD99 and nuclear positivity for NKX2.2 in the small round cell component of the tumor. Molecular analysis revealed EWSR1/FLI fusion. The diagnosis then considered a "Ewing Sarcoma Displaying Extensive Well Differentiated Neuroblastomatous Differentiation".

CONCLUSION

Tumors with the EWSR1/FLI fusion may show neuroblastomatous differentiation. We chose to treat this as an Ewing Sarcoma (ES). Recognition of this phenomenon in ES cases may prevent a possible misinterpretation and a failure in oncologic treatment.

Primitive Neuroectodermal Tumors of the Female Genital Tract: A Morphologic, Immunohistochemical, and Molecular Study of 19 Cases

Primary primitive neuroectodermal tumor (PNET) of the female genital tract is rare, and its proper classification remains unclear. The clinical, histologic, and immunophenotypic features as well as EWSR1 rearrangement status of 19 gynecologic PNETs, including 10 ovarian, 8 uterine, and 1 vulvar tumors, are herein reported. Patient age ranged from 12 to 68 years, with a median age of 20 and 51 years among those with ovarian and uterine PNETs, respectively. Morphologic features of central nervous system (CNS) tumors were seen in 15 PNETs, including 9 medulloblastomas, 3 ependymomas, 2 medulloepitheliomas, and 1 glioblastoma, consistent with central PNET. The remaining 4 PNETs were composed entirely of undifferentiated small round blue cells and were classified as Ewing sarcoma/peripheral PNET. Eight PNETs were associated with another tumor type, including 5 ovarian mature cystic teratomas, 2 endometrial low-grade endometrioid carcinomas, and a uterine carcinosarcoma. By immunohistochemistry, 17 PNETs expressed at least 1 marker of neuronal differentiation, including synaptophysin, NSE, CD56, S100, and chromogranin in 10, 8, 14, 8, and 1 tumors, respectively. GFAP was positive in 4 PNETs, all of which were of central type. Membranous CD99 and nuclear Fli-1 staining was seen in 10 and 16 tumors, respectively, and concurrent expression of both markers was seen in both central and Ewing sarcoma/peripheral PNETs. All tumors expressed vimentin, whereas keratin cocktail (CAM5.2, AE1/AE3) staining was only focally present in 4 PNETs. Fluorescence in situ hybridization was successful in all cases and confirmed EWSR1 rearrangement in 2 of 4 tumors demonstrating morphologic features of Ewing sarcoma/peripheral PNET and concurrent CD99 and Fli-1 expression. In conclusion, central and Ewing sarcoma/peripheral PNETs may be encountered in the female genital tract with central PNETs being more common. Central PNETs show a spectrum of morphologic features that overlaps with CNS tumors but lack EWSR1 rearrangements. GFAP expression supports a morphologic impression of central PNET and is absent in Ewing sarcoma/peripheral PNET. Ewing sarcoma/peripheral PNETs lack morphologic features of CNS tumors.