A 46-year-old nonsmoking Honduran woman presented with syncope and a 2.6 cm left lower lobe lesion. Workup showed lung adenocarcinoma with 30% PDL1 expression and NGS testing showed RET pathogenic fusion of KIF5B-RET on exon 12. After lobectomy and adjuvant chemotherapy, recurrence occurred 21 months later. She was treated with pembrolizumab and pemetrexed, but the disease progressed. After starting selpercatinib, her disease remained stable for 10 months. A 35-year-old nonsmoking Honduran man presented with shortness of breath and a 4.9 x 3.9 cm right upper lobe mass with metastasis. Biopsy showed poorly differentiated non-small cell carcinoma, and NGS revealed a KIF5B-RET
fusion. He initially received carboplatin and paclitaxel before starting selpercatinib but passed away despite a partial response. Discussion: There has been a slight increased incidence of RET mutated lung adenocarcinomas reported in Asian patients compared to White and Black patients. There has been no known association between RET mutations and the Central American population. There is a possible geographic and environmental association of RET mutated lung cancers. Further understanding of RET mutated malignancies has great clinical significance given the advent of precision medicine and the development of TKI’s that can selectively inhibitor activated RET tyrosine kinase receptors.
RIGHT ARM FRACTURES AND EDEMA IN THE SETTING OF HIGH-GRADE NEUROENDOCRINE CARCINOMA Thomas Deiss, Colin Cunningham, Sanjay Kamboj; Louisiana State University, New Orleans, LA.
Introduction: Poorly differentiated neuroendocrine carcinoma can be difficult to diagnose and treat due to the heterogenous and aggressive nature of the disease. Case: A 56-year-old male presented due to increasing pain and swelling of his right upper extremity (RUE). He also reported weight loss of 25 pounds over the previous three months. The patient stated the pain and swelling began four months ago but significantly worsened in the two days prior to admission. One month prior to admission the patient presented to an outside facility and an x-ray of his RUE showed pathological fractures of the humerus and multiple lytic lesions. Plans were made for a future biopsy. The physical exam was notable for an edematous RUE that was tender to palpation, with limited range of motion. Computed tomography (CT) imaging revealed a large soft tissue lesion with lytic changes in the proximal humerus, right axillary and subaortic lymphadenopathy, and thickening of the left adrenal gland. Pathology from a right humerus biopsy showed poorly differentiated carcinoma with extensive necrosis. A right axillary lymph node and additional right humerus bone biopsy was then performed, which
showed metastatic high-grade carcinoma with neuroendocrine features, non-specific with respect to the site of origin. Given the aggressive nature of his malignancy and rapid progression, he received five fractions of radiation therapy simultaneously with his first cycle of chemotherapy while inpatient. He was discharged and later received his second cycle outpatient with carboplatin, etoposide, and atezolizumab. Cycle three of chemotherapy was delayed due to three separate hospitalizations for hypercalcemia, left intertrochanteric fracture after a fall, and symptomatic anemia, respectively. CT imaging of his head during the final admission showed multiple lesions with surrounding vasogenic edema, suggestive of metastases. Based on his progression of disease and poor prognosis, the patient was transitioned to comfort-focused care after discussing with the patient and family. Discussion: This case illustrates a unique presentation of metastatic high-grade carcinoma with neuroendocrine features and the difficulties of disease management. Despite initiation of proper multimodal treatment, the rapid progression limited treatment and prevented the discovery of the primary site of origin.
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