Osimertinib Resistance via Histologic Transformation From Non-small Cell Lung Carcinoma to Carcinosarcoma.

Resistance to tyrosine kinase inhibitors (TKIs) in non-small cell lung carcinoma (NSCLC) remains a significant clinical challenge. Osimertinib, a third-generation TKI, has demonstrated efficacy in overcoming resistance, but novel resistance mechanisms continue to emerge. This case report presents a unique instance of histologic transformation from NSCLC to carcinosarcoma, representing a previously unreported manifestation of osimertinib resistance. We describe the clinical course of a 63-year-old female with epidermal growth factor receptor (EGFR)-mutant NSCLC who initially responded to osimertinib but eventually developed carcinosarcoma. The transformation was associated with additional EGFR mutations and alterations in RB and TP53. Despite aggressive treatment, the patient's condition deteriorated, emphasizing the limited therapeutic options for carcinosarcoma. This case underscores the need for further research to elucidate the molecular mechanisms behind histologic transformation and explore novel therapeutic strategies to address osimertinib resistance in NSCLC. Understanding and addressing these mechanisms are crucial for improving outcomes in patients facing this challenging form of resistance.

Core needle biopsy for the diagnosis of primary soft tissue lesions: Accuracy and diagnostic challenges.

BACKGROUND: Core needle biopsy (CNB) and fine needle aspiration (FNA) are currently the most common biopsy methods for investigation of soft tissue lesions. Selection of the method to be used depends on a number of factors including diagnostic accuracy, local expertise with the techniques and the need for ancillary testing. We investigated the diagnostic accuracy of CNB and factors influencing the selection of CNB or FNA. METHODS: An electronic search of the surgical pathology records for all core needle biopsies of soft tissue lesions with subsequent incisional biopsies or excisions between January 1, 2015 and December 31, 2021 was performed. Searches of the literature for publications documenting diagnostic accuracy of core biopsy and FNA were performed using the Pub Med literature data base. RESULTS: The electronic search yielded 177 CNBs with appropriate follow-up. Six cases were non-diagnostic. The remaining 171 cases showed an accuracy of 90% for separation of benign from malignant with two false-positive and 17 false-negative diagnoses. The literature search revealed 11 series of CNBs with a diagnostic accuracy of 74% to 97%. The literature search revealed 20 series of FNAs with an accuracy of 84.8% to 100% for separation of benign from malignant. CONCLUSIONS: Core needle biopsy is a highly accurate diagnostic technique with an accuracy of 90% for separation of benign from malignant lesions. The percentage of non-diagnostic cases is low (3.4%). No significant biopsy related complications were seen in this study.

A report of an intracortical chondroblastoma of the diaphysis in a skeletally mature patient.

Chondroblastomas characteristically occur in skeletally immature patients, and arise within the medullary canal of the epiphysis. We report a rare case of an intracortical chondroblastoma arising in the diaphysis, and occurring in an adult in his 3rd decade of life. Immunohistochemistry results were critical to confirmation of this rare diagnosis, with immunohistochemistry showing S100, DOG1, and H3K36me3 positivity in the neoplastic cells.