ABSTRACT
The 5th WHO classification of thoracic tumours includes thoracic SMARCA4-deficient undifferentiated tumour (SMARCA4-UT) among the "other epithelial tumours of the lung" chapter. Herein, we present a case of undifferentiated thoracic neoplasm with retention of SMARCA4 expression, lack of NUT fusion protein and loss of SMARCB1/INI1 expression. After presenting the clinical and pathological features of the tumour, we carried out a review of the literature on the same topic. Albeit very rare, we believe this entity should be included in the heterogeneous group of undifferentiated neoplasms of the thorax.
Subject(s)
DNA Helicases , SMARCB1 Protein , Thoracic Neoplasms , Transcription Factors , Humans , SMARCB1 Protein/deficiency , SMARCB1 Protein/genetics , Transcription Factors/genetics , Transcription Factors/deficiency , Thoracic Neoplasms/pathology , Thoracic Neoplasms/genetics , DNA Helicases/deficiency , DNA Helicases/genetics , Nuclear Proteins/genetics , Nuclear Proteins/deficiency , Male , Female , Biomarkers, Tumor/analysis , Biomarkers, Tumor/genetics , Middle Aged , Lung Neoplasms/pathology , Lung Neoplasms/genetics , Lung Neoplasms/diagnosisABSTRACT
More than 95% of patients with acute promyelocytic leukemia (APL) are characterized by the reciprocal translocation t(15;17)(q24;21), which involves the promyelocytic leukemia protein (PML) gene on chromosome 15 and the retinoic acid receptor-α (RARA) gene on chromosome 17, leading to the production of the PML::RARA chimeric gene. Additional chromosomal abnormalities are described in all acute myeloid leukemias and occur in approximately one-third of patients with newly diagnosed APL. Here, we report the case of de novo APL showing the classical t(15;17)(q24;q21), a deletion of the short arm of chromosome 6 (6p), and a noncanonical molecular variant of the PML::RARA transcript. Nevertheless, the patient achieved complete remission after treatment with conventional therapy with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). Notwithstanding that the molecular pathogenesis of this type of atypical variant still remains unknown, we conclude that this atypical PML::RARA bcr2 fusion gene associated with del(6p) does not seem to alter the effectiveness of combined treatment with ATRA and ATO.