Ewing sarcoma family of tumours: unusual histological variants and immunophenotypic characteristics

Ewing sarcoma of the mandible: A rare case report and literature review

Ewing sarcoma (ES) usually arises from long bones and affects the head and neck region in only 1%-4% of cases. We reported clinical, radiographic, cytomorphologic, and histomorphologic findings of the ES in the mandible, because of its rarity and radiologically misinterpreted as a parotid gland tumor. A 26-year-old male patient presented with a history of painfull cheek swelling. On magnetic resonance imaging, a mass measuring 50 × 48 × 45 mm was found eroding mandible and pushing back the parotid gland. Aspiration cytology was performed with suspicion of parotid gland tumor. Small, nucleated cells with nuclear indentation, inconspicuous nucleoli, and occasionally rosette-like arrangement were observed. Neuroendocrine immune markers were positive on cell block. It was diagnosed as small round cell neoplasm with neuroendocrine differentiation and biopsy was suggested. The differential diagnosis considered soft tissue and parotid gland tumors. The small round cell tumor morphology was seen on biopsy specimen and immunostaining was applied. The diagnosis for this case was ES of the mandible. ES of the mandible is unusual. Although the histogenesis is still unknown, various cells have been proposed as cells of origin namely, endothelial, hematopoietic, fibroblastic, mesenchymal stem cells or neural derived mesenchymal stem cells. Small cell morphology, CD99, CD56, neuron specific enolase, and synaptophysin expressions confirmed the diagnosis of ES. The differentiation of the ES from other small cell tumors may be difficult and requires awareness for histological and immunohistochemical features. It should be kept in mind that the diagnosis can be challenging due to uncommon locations and radiological misinterpreted.

Adamantinoma-Like Ewing Sarcoma of the Parotid Gland: Report of Two Cases and Review of Literature

Adamantinoma-like Ewing sarcoma (ALES) is a rare variant of Ewing sarcoma. It demonstrates heterogeneous morphologic pattern and complex immunophenotypic profile, with a peculiar combination of epithelial and neuroendocrine differentiation. ALES is rarely reported in the head and neck areas, including the parotid salivary gland. Till now, only 10 cases of ALES have been reported in the salivary glands. Herein, we report two cases of ALES involving the parotid gland, adding some valuable insight to the recently reported cases at this site.

PNET with neuroendocrine differentiation of the lung: Report of an unusual entity

Ewing's sarcoma/primitive neuroectodermal tumor (PNET) has been the subject of recent reports describing morphologic variants (adamantinoma-like, large cell, spindle cell, sclerosing, clear cell, and vascular-like) of the most classic form, as well as cases displaying unusual morphologic differentiation and atypical immunohistochemical features. We report a case of an uncommon lung tumor in a 20-year-old female, morphologically and molecularly consistent with an Ewing's sarcoma/PNET tumor with foci of squamous differentiation, and peculiar expression of vimentin, high-molecular-weight keratins, p63, synaptophysin, and chromogranin. This case raises a challenging differential diagnostic problem with therapeutic implications: Should the patient be treated following the protocols for Ewing's sarcoma/PNET tumors or as for lung carcinoma with neuroendocrine features? The patient we report here was treated with neoadjuvant chemotherapy for Ewing's sarcoma/PNET according to Euro Ewing 99 study protocol followed by surgery and has no evidence of disease 15 months after the initial diagnosis. This highlights the importance of achieving the correct diagnosis of these atypical tumors using all clinical, morphological, and ancillary methods available to allow for their correct and timely treatment.