The evolution of DNA methylation at genome level and methylation intra-tumor heterogeneity (ITH) during early lung carcinogenesis has not been systematically studied. We performed multiregional reduced representation bisulfite sequencing (RRBS) of 62 resected lung nodules from 39 patients including atypical adenomatous hyperplasia (AAH, n=14), adenocarcinoma in situ (AIS, n=15), minimally invasive adenocarcinoma (MIA, n=22), and invasive adenocarcinoma (ADC, n=11). We observed significantly higher level of methylation ITH in later-stage lesions and gradual increase in both hyper- and hypomethylation compared to matched normal lung tissues over the course of neoplastic progression. The phyloepigenetic patterns inferred from methylation aberrations resembled those based on somatic mutations suggesting parallel methylation and genetic evolution during the early lung carcinogenesis. De-convolution of transcriptomic profiles from a previously published cohort and RBBS data from the current cohort demonstrated higher ratios of T regulatory cells (Tregs) versus CD8+ T cells in later-stage diseases implying progressive immunosuppression with neoplastic progression. Furthermore, increased global hypomethylation was associated with higher mutation burden, higher copy number aberration burden, higher allelic imbalance burden as well as higher Treg/CD8 ratio highlighting the potential impact of methylation states on chromosomal instability, mutagenesis and the tumor immune microenvironment.

The evolution of DNA methylation at genome level and methylation intra-tumor heterogeneity (ITH) during early lung carcinogenesis has not been systematically studied. We performed multiregional reduced representation bisulfite sequencing (RRBS) of 62 resected lung nodules from 39 patients including atypical adenomatous hyperplasia (AAH, n=14), adenocarcinoma in situ (AIS, n=15), minimally invasive adenocarcinoma (MIA, n=22), and invasive adenocarcinoma (ADC, n=11). We observed significantly higher level of methylation ITH in later-stage lesions and gradual increase in both hyper- and hypomethylation compared to matched normal lung tissues over the course of neoplastic progression. The phyloepigenetic patterns inferred from methylation aberrations resembled those based on somatic mutations suggesting parallel methylation and genetic evolution during the early lung carcinogenesis. De-convolution of transcriptomic profiles from a previously published cohort and RBBS data from the current cohort demonstrated higher ratios of T regulatory cells (Tregs) versus CD8+ T cells in later-stage diseases implying progressive immunosuppression with neoplastic progression. Furthermore, increased global hypomethylation was associated with higher mutation burden, higher copy number aberration burden, higher allelic imbalance burden as well as higher Treg/CD8 ratio highlighting the potential impact of methylation states on chromosomal instability, mutagenesis and the tumor immune microenvironment.

Intraarticular masses are infrequently encountered in clinical practice; however, the differential diagnosis can be broad. Neoplasia, both benign and malignant, and proliferative processes are the most common etiologies. We present a case of metastatic disease in the synovium in a patient with a history of lung cancer. Lung carcinoma is the most common primary malignancy to metastasize to synovial tissue, and the knee joint is the most common joint to be affected. I n this report, we discuss the diff erential considerations for intraarticular masses and the clinical presentation of metastatic synovial disease. We discuss some fi ndings that are classic for specifi c entities; however, many radiologic fi ndings concerning synovial pathology are nonspecifi c. As the diff erential considerations for intraarticular masses are vast, clinical history is often as necessary as radiologic fi ndings to elucidate the correct diagnosis. CASE PRESENTATIONA 61-year-old man who underwent a left pneumonectomy for cancer 4 months before presentation complained of knee pain with swelling since the operation. Th e knee joint was aspirated, and the fl uid demonstrated infl ammatory white blood cells but was negative for microorganisms. A diagnosis of rheumatoid arthritis had been made in the past, but the knee pain had never been of this character or intensity. Th e patient was unable to bear weight or straighten his leg in the emergency room. On examination, he was afebrile, normotensive, and tachycardic, with underlying atrial fi brillation and a ventricular rate of 90 to 127 beats per minute. Th e knee was edematous, erythematous, and warm with a range of motion of <90°. His leukocyte count was 23,600 cells/mL.Conventional gadolinium-enhanced magnetic resonance (MR) imaging of the left knee revealed diff use enlargement of the knee joint space secondary to multilobulated and heterogenous mass-like structures (Figures 1-4). Th ese structures demonstrated heterogeneously increased T2 hyperintense and intermediate T1 intensity characteristics. Most of the joint space was replaced by hyperenhancing synovium. Enlarged lymph nodes were seen in the popliteal fossa. At that time, diff erential considerations included severe infl ammatory arthritis and rather than unusual metastasis. Surgical pathology showed a diagnosis of synovial metastasis from primary large-cell lung carcinoma. DISCUSSIONApproximately 48 cases of synovial metastasis have been reported. Adenocarcinoma has been the most common type of synovial metastasis encountered. Despite the highly vascular nature of synovial tissue, neoplastic masses in articular spaces are much less frequently encountered than mass lesions secondary to infectious and infl ammatory arthritides. If intraarticular masses are discovered when they are still small, the tissue of origin such as synovium or cartilage may be delineated. However, commonly both cell types are involved, and the type can be impossible to decipher when the mass is as large, as in the case presented. Primary lung cancer is the ...