(P 286) ADAMANTINOMA - LIKE EWING SARCOMA WITH ATYPICAL PRESENTATION AND FATAL OUTCOME IN 20-YEAR-OLD WOMAN - A CASE REPORT

Objective: Adamantinoma-like Ewing sarcoma (ALES) is an ultra-rare disease described in literature with a broad range of clinical presentations and outcomes. The disease has traditionally been regarded as a variant of Ewing sarcoma (ES), harboring EWS1-FLI1 translocation but with a strong epithelial differentiation. Research during the last year has shown a specific methylation profile, arguing that ALES may represent a specific entity of tumors rather than a subclass of ES. We present a case with a formerly not described clinical presentation of ALES, including a widespread disease causing initially limited symptoms. However, the patient's condition rapidly deteriorated.

Methods: A 20-year-old, formerly healthy woman, sought care in the summer of 2023 presenting one week's history of slurred speech and difficulties of swallowing. For two days she was also tired and had a headache. Two weeks earlier she had been on vacation with her family. The patient was diagnosed with a bilateral hypoglossal palsy, confirmed by a neurologist, who also detected bilateral positive Babinski's sign. The neurological status was otherwise without objection. Clinical diagnosis was a neurological withdrawal syndrome, emanating from the brain stem or higher medulla, most probably caused by inflammatory or infectious disease. MRI of brain and spine, however, revealed a generalized malignancy, infiltrating bonemarrow and dura, with widespread soft tissue tumours in neck, thorax and abdomen, ascites, and right-side pleural effusion. A PET-CT scan (figure will be added) showed multiple metastases in lung, liver, lymph nodes, subcutis, the whole skeleton, and also a large pelvic mass. Blood samples showed anemia (Hb 85 g/L), elevated SR (69 mm) and slightly elevated liver-function tests. After high dose of betamethasone the neurological symptoms related to hypoglossal palsy promptly disappeared.
Biopsies, lumbar punction and bone marrow biopsy found a highly malignant small round tumor with a desmoplastic, hyalinized stroma. Morphologically the tumor was not considered a classical ES, rhabdomyosarcoma or lymphoma. Differential diagnoses considered were small cell neuroendocrine carcinoma, desmoplastic small round cell tumor and small cell carcinoma of the ovary. Immunostains were not conclusive.
Clinically, the patient deteriorated very fast. In just one week she was completely bedridden, and due to progression of tense abdomen and breathing difficulties she had both a pleural and ascites drainage. She had no appetite and was supported with total parenteral nutrition.
Realizing the patient was in a fatal, rapidly worsening condition we made the decision, together with the woman and her parents, to start up chemotherapy with ifofasfamide-etoposide in doses according to EuroEwing 2012. She received one course without any sign of improvement. Less than three weeks after the first examination the patient was discharged from hospital with advanced care at home. Four days later the patient passed away.

Results: Ten days after the death of the patient the pathology consult report from Dr Christopher Fletcher, Boston, arrived. The immunophenotype and molecular findings gave the diagnosis of "round cell malignant neoplasm with squamous differentiation"; so-called "adamentinoma-like Ewing sarcoma". Immunostains had confirmed positive staining for pan-keratin, CK20, p40 and CD99, and FISH-analysis for EWSR1 gene rearrangement was positive. The findings will be presented in details (figures).

Conclusion: This case shows a very aggressive form om the adamantinoma-like Ewing sarcoma, surprisingly with initially mild symptoms, although a disseminated malignancy. There is still a controversy regarding classification of this tumor type, and further investigations is needed to find out if ALES should be considered as a variant of Ewing sarcoma or a true carcinoma, although positive for the EWSR1 gene rearrangement.