Primary cutaneous/subcutaneous Ewings sarcoma

Amongst Ewing sarcoma family of tumours, (EFST), cutaneous/subcutaneous Ewing sarcoma are defined as tumours arising from cutaneous or subcutaneous tissue, not invading the underlying aponeurosis. They are rare tumours, with less than 200 patients published. They are typically small tumours (less than 5cm), and can arise at any anatomical location, with a particular tropism for distal, truncal and head/neck locations, compared to classical Ewing sarcoma. Like other conjunctive tumours, they have to be treated in specialized centers, with a diagnostic procedure following ESMO guidelines about soft-tissue tumours, favoring a core needle biopsy in most cases. They share classical pathological and molecular features of EFST (including EWSR1 rearrangement). Metastatic presentation is rare (less than 5% at diagnosis), but must be carefully searched using appropriated imaging considered the bad prognosis of these patients. Treatment strategy relies on neoadjuvant and adjuvant chemotherapy, surrounding the local treatment. Patients with localized disease have good prognosis and have to be treated with the dual objective of curability, and of minimizing acute and late toxicity. That is why in case of small tumours (<200mL), patients can be treated with less intensive protocols, as Saint Jude's (low-dose semi-continuous cyclophosphamide/doxorubicin regimen as induction chemotherapy and vincristine/actinomycin courses as maintenance therapy), setting aside the option of classical VDC/IE protocol for larger tumors. Local treatment must rely on carcinologic surgery, with the aim to avoid radiotherapy when possible. Patients with metastatic disease have bad prognosis resemble classical Ewing sarcoma, and have to be treated accordingly.

Merkel cell carcinoma: an update

Merkel cell carcinoma (MCC) is an uncommon primary cutaneous neuroendocrine carcinoma associated with an adverse prognosis. In recent years, our understanding of MCC biology has markedly progressed. Since the discovery of the Merkel cell polyomavirus, it has become clear that MCC represents an ontogenetically dichotomous group of neoplasms with overlapping histopathology. Specifically, most MCCs arise secondary to viral oncogenesis, while a smaller subset is the direct result of UV-associated mutations. The distinction of these groups bears relevance in their immunohistochemical and molecular characterization, as well as in disease prognosis. Further recent developments relate to the landmark utilization of immunotherapeutics in MCC, providing optimistic options for the management of this aggressive disease. In this review, we discuss both fundamental and emerging concepts in MCC, with a particular focus on topics of practical relevance to the surgical or dermatopathologist.

Cutaneous Ewing Sarcoma Presenting as a Second Primary Malignancy in a Child

Ewing sarcoma is an EWS-ETS family member-driven malignancy that most commonly arises from bone. Cutaneous Ewing sarcoma is a rare variant which harbors an EWS-ETS family fusion but demonstrates an immunohistochemical staining pattern distinct from classic Ewing tumors. EWSR1 fluorescence in situ hybridization testing interpretation can be challenging in the setting of cutaneous Ewing sarcoma, making an integrated histologic and sequencing approach key for an accurate diagnosis. Here, we report a pediatric patient with a history of neuroblastoma treated with surgery only that developed a cutaneous nodule and was diagnosed with cutaneous Ewing sarcoma as a second primary cancer.

A large femoral primary cutaneous Ewing's sarcoma in a 35-year-old woman: Case report

INTRODUCTION

Extraskeletal Ewing's sarcoma is a rare malignant tumor of mesenchymal origin, which is histologically similar to primary osseous Ewing's sarcoma. It has been well described in deep soft tissues. However, location in cutaneous or subcutaneous tissue has rarely been reported. Being seen principally in children, it can be seen, rarely, in old men.

CASE PRESENTATION

We present a case of large primary cutaneous Ewing sarcoma within the left thigh of a 35-year-old woman, without osseous involvement. Physical examination. Histologically, it was a small round cell tumor that marked strongly for CD99. The diagnosis of cutaneous Ewing sarcoma was performed.

DISCUSSION

The things that distinguish our case are that it is the first case in Syria, in addition to the size of the large tumor with diameters of 15 × 20 cm, and it is in a 35-year-old woman.

CONCLUSION

Ewing sarcoma is a rare malignant small round cell tumor of the skin and subcutaneous tissue. It should be differentiated from other cutaneous neoplasms composed of small round cells.

Recurrent Subcutaneous Ewing Sarcoma on 18F-FDG PET/CT

ABSTRACT

Subcutaneous Ewing sarcoma is very rare. This report presents the case of a 23-year-old woman with a history of primary subcutaneous Ewing sarcoma who recently found a gradually increasing mass. Recurrent subcutaneous Ewing sarcoma was thus suspected. 18F-FDG PET/CT was performed and showed an FDG-avid mass in her buttocks. Subsequent histopathological and immunohistochemical tests were consistent with subcutaneous Ewing sarcoma.

Merkel cell carcinoma: A review

Merkel cell carcinoma has been a focus of active scientific investigation in recent years and new information on the topic has emerged. Although uncommon, this primary cutaneous neuroendocrine carcinoma, usually involving the head/neck of elderly individuals, has a poor prognosis. Within the past two decades, an increase in the incidence of the tumor and the discovery of its link to the Merkel cell polyomavirus have focused medical attention on the lesion. The resulting studies have improved our understanding of the biology of the neoplasm and contributed to clinical care. Specifically, two pathogenic subsets of the tumor have come to light, the majority due to Merkel cell polyomavirus and the minority caused by ultraviolet radiation-induced genetic damage. This dichotomy carries prognostic implications favoring the former subset. In addition, having capitalized on the known susceptibility of the tumor to immune influences, investigators have recently discovered its responsiveness to immune checkpoint inhibition. This revelation has constituted a therapeutic milestone at the clinical level. Herein we provide an overview of the topic, outline updates in the field and place an emphasis on dermatopathologic aspects of Merkel cell carcinoma.

Ewing-Like Sarcoma: A Case of a Primary Cutaneous Primitive Neuroectodermal Tumor With Atypical Immunohistochemistry and Lack of Fusion Oncogene Detection

We present a 25-year-old male patient with a primary cutaneous primitive neuroectodermal tumor (cPNET) with unusual immunohistochemistry and lack of fusion oncogene generation. The lesion expressed CD99 and WT-1, and the histological features were consistent with cPNET. Differential diagnoses such as rhabdomyosarcoma, desmoplastic small round blue cell tumor, hematolymphoid neoplasm, neuroblastoma, and CIC-DUX round cell sarcoma were ruled out based on immunohistochemistry, genetic studies, and histology. Previous cPNET cases have been published detailing abnormal immunochemistry and genetic expression. However, to our knowledge, fusion oncogene negativity in cPNET tumors has only been reported in one other published case series. These reports, including this study, reinforce the fact that a high index of suspicion should be used when diagnosing these tumors, regardless of immunohistochemical and genetic variability. This case highlights that the typical genetic and immunohistochemical features of cPNET may be more variable than previously thought. Future studies are needed to better understand these variations of cPNET.