A rare case of combined small cell lung carcinoma with heterologous component of rhabdomyosarcoma diagnosed by endobronchial ultrasound (EBUS)-guided biopsy.

We describe an unusual case of combined small cell lung carcinoma (SCLC) with a heterologous sarcomatous component of rhabdomyosarcoma in a 61-year-old male smoker. The diagnosis was made using endobronchial ultrasound (EBUS)-guided fine needle aspiration and biopsy. This report highlights the challenges of diagnosing small round blue cell tumors in limited material and the importance of ancillary testing. The histologic diagnosis informed clinical management and therapy.

Concerted epithelial and stromal changes during progression of Barrett's Esophagus to invasive adenocarcinoma exposed by multi-scale, multi-omics analysis.

Esophageal adenocarcinoma arises from Barrett's esophagus, a precancerous metaplastic replacement of squamous by columnar epithelium in response to chronic inflammation. Multi-omics profiling, integrating single-cell transcriptomics, extracellular matrix proteomics, tissue-mechanics and spatial proteomics of 64 samples from 12 patients' paths of progression from squamous epithelium through metaplasia, dysplasia to adenocarcinoma, revealed shared and patient-specific progression characteristics. The classic metaplastic replacement of epithelial cells was paralleled by metaplastic changes in stromal cells, ECM and tissue stiffness. Strikingly, this change in tissue state at metaplasia was already accompanied by appearance of fibroblasts with characteristics of carcinoma-associated fibroblasts and of an NK cell-associated immunosuppressive microenvironment. Thus, Barrett's esophagus progresses as a coordinated multi-component system, supporting treatment paradigms that go beyond targeting cancerous cells to incorporating stromal reprogramming.

Clinically Occult Diffuse Pleural Mesothelioma in Patients Presenting With Spontaneous Pneumothorax.

OBJECTIVES: To report histologic features of unsuspected diffuse pleural mesothelioma (DPM) in surgical specimens for pneumothorax and demonstrate how ancillary markers support a diagnosis of malignancy in this context. We explored whether pneumothorax may be a clinical manifestation of mesothelioma in situ (MIS). METHODS: A single-institution database search identified patients who underwent surgical resection for spontaneous pneumothorax (n = 229) and/or were diagnosed with DPM (n = 88) from 2000 to 2020. RESULTS: Spontaneous pneumothorax without clinical, radiologic, or intraoperative suspicion of mesothelioma was the initial presentation in 2 (2.3%) of 88 patients diagnosed with DPM. This represented 0.9% (2/229) of all patients undergoing surgical management of pneumothorax but accounted for a larger proportion of older patients (12.5% older than 70 years). Immunohistochemistry for BAP-1 and/or MTAP confirmed the diagnosis of DPM in 2 cases. Mesothelioma in situ was identified retrospectively by immunohistochemistry in 1 case of spontaneous pneumothorax from a 77-year-old man who developed invasive DPM 25 months later. No additional cases of MIS were identified in 19 surgical lung resections for spontaneous pneumothorax. CONCLUSIONS: Histologic examination of bleb resections with ancillary testing for cases with ambiguous features is essential for detection of early DPM. It is uncertain whether spontaneous pneumothorax may represent a clinical manifestation of MIS.

Hypersensitivity Pneumonitis: Updates in Evaluation, Management, and Ongoing Dilemmas.

Hypersensitivity pneumonitis (HP) is a heterogenous disease entity characterized by an aberrant immune response to inhalational antigens. Disease modification hinges on early antigen remediation with a goal to attenuate immune dysregulation. Disease severity and progression are mediated by an interface between degree, type and chronicity of exposure, genetic predisposition, and biochemical properties of the inducing agent. Guidelines have provided a standardized approach; however, decision-making remains with many clinical dilemmas. The delineation of fibrotic and nonfibrotic HP is crucial to identify the differences in clinical trajectories, and further clinical trials are needed to understand optimal therapeutic strategies.

Esophageal Cancer Genetics and Clinical Translation.

Comprehensive genomic profiling has advanced our understanding of the molecular basis of esophageal cancer. Marked genomic heterogeneity between individual patients and the 2 major histologic subtypes of esophageal cancer likely contributes to the poor survival and lack of universally effective therapies. Esophageal adenocarcinoma and squamous cell carcinoma are molecularly and biologically distinct entities, with unique risk factors and geographic distributions that may benefit from individualized treatment strategies. Molecular characterization of tumors enables personalized care by providing prognostic information and identifying those most likely to benefit from targeted therapy and/or immunotherapy.

A 30-Year-Old Immune Deficient Woman With Persistent Cough and Shortness of Breath.

CASE PRESENTATION: A 30-year-old woman was referred with increasing shortness of breath and cough in the setting of GATA2 deficiency. She initially presented 9 years previously with recurrent episodes of pneumonia and sinusitis. Genetic testing revealed a heterozygous GATA2 mutation (c.988C>T). She has since had multiple infections that have included necrotizing fasciitis of the right thumb, recurrent pilonidal infections (which required 23 procedures), esophageal candidiasis, and human papillomavirus-positive high-grade squamous intraepithelial lesion of the cervix. Serial bone marrow biopsy specimens showed persistent hypocellularity (20% to 60%) with intermittent erythroid atypia and variable detection of trisomy 8, which were concerning for evolving myelodysplastic syndrome. One year before the current admission, she was diagnosed with disseminated Mycobacterium avium complex and was treated with rifabutin, ethambutol, and azithromycin. She was taking voriconazole, acyclovir, and trimethoprim-sulfamethoxazole prophylaxis.

Resectability, Recurrence, and Risk Stratification of Giant Solitary Fibrous Tumors in the Thoracic Cavity.

BACKGROUND: Solitary fibrous tumors (SFTs) are rare mesenchymal tumors most commonly arising from the pleura in the thoracic cavity. The impact of tumor size on risk of recurrence in thoracic SFTs is not well understood. METHODS: A single institution review was performed on all resected thoracic SFTs (1992-2019) with giant SFT defined as ≥ 15 cm. Clinical information, pathologic characteristics, and long-term survival data were collected, and predictors of recurrence and survival were evaluated with regression and Kaplan-Meier analysis. RESULTS: There were 38 thoracic SFTs resected from patients, with the majority of tumors (n = 23, 60.5%) originating from visceral pleura. There were nine (23.7%) giant SFTs with a mean size 20.4 cm (range 17-30 cm). Mean follow-up time was 81.0 months (range 1-261 months), during which 4 of 38 (10.5%) patients experienced a recurrence within the thorax (range 51-178 months). The presence of tumor necrosis (p = 0.021) and ≥ 4 mitoses per high-powered field (p = 0.010) were associated with SFT recurrence on univariate regression. Overall 5-year, 10-year, and 20-year survival was 78.2%, 72.6%, and 42.4%, respectively, and SFT-related mortality occurred in three patients at 83, 180, and 208 months postoperatively. There were no recurrences or SFT-related mortality among patients with giant SFT. CONCLUSION: This study represents one of the largest contemporary single institution reviews of long-term outcomes of giant thoracic SFT. Our data suggest that size is not a risk factor for recurrence in thoracic SFTs and long-term survival is excellent for giant SFTs.

Diagnosis of Mesothelioma.

Mesothelioma is a rare neoplasm that arises from mesothelial cells lining body cavities including the pleura, pericardium, peritoneum, and tunica vaginalis. Most malignant mesotheliomas occur in the chest and are frequently associated with a history of asbestos exposure. The diagnosis of malignant mesothelioma is challenging and fraught with pitfalls, particularly in small biopsies. This article highlights what the pathologist needs to know regarding the clinical and radiographic presentation of mesothelioma, histologic features including subtypes and variants, and recent advances in immunohistochemical markers and molecular testing.

Clinicopathological features and outcomes of parenchymal rejection in liver transplant biopsies.

AIMS: The aim of this study was to perform a comprehensive retrospective analysis of liver transplant biopsies with parenchymal rejection (PR) at our institution, including histological features, laboratory values and follow-up biopsies, and to compare PR with portal-based acute cellular rejection (ACR). METHODS AND RESULTS: Biopsies from 173 patients were evaluated (retrospective database search 1990-2017), including 49 isolated PR, 35 PR with portal ACR (PR/ACR), 34 mild ACR and 52 moderate ACR cases. The rise and fall of serum liver enzymes was calculated as a measure of acute liver injury and response to immunotherapy, respectively. Isolated PR was associated with delayed-onset acute rejection (P < 0.001), as well as younger age (P = 0.004), and showed a similar rise in liver enzymes to mild ACR. PR/ACR and moderate ACR showed the highest elevations in transaminases (P < 0.05). Isolated PR on an initial biopsy was associated with recurrent episodes of PR (P = 0.01), chronic ductopaenic rejection (P = 0.002) and chronic vascular rejection (P = 0.017). Immunohistochemistry for C4d was performed, and strong C4d staining of venules was only detected in one severe isolated PR case (one of three, 33%) and one moderate ACR case (one of 20, 5%). CONCLUSIONS: Isolated PR represents a form of late acute rejection with distinct clinical and histological features. There is value in reporting PR in liver transplant biopsies to identify patients at higher risk of developing recurrent PR and chronic rejection. Standardisation of terminology and histological criteria of PR can help in uniform reporting and ensure appropriate management.

Case report: recurrent metastatic breast cancer in internal mammary dissection bed discovered at the time of coronary bypass.

INTRODUCTION: Many patients who undergo coronary artery bypass surgery have a prior history of cancer and potentially chest radiation which is a known risk factor for coronary atherosclerosis. Prior radiation increases fibrosis and can make the dissection of the left internal mammary artery (LIMA) more challenging. CASE REPORT: A 72-year-old woman with a history of stage IIA pT2N0M0 left breast intraductal carcinoma treated with lumpectomy, adjuvant chemotherapy and radiation therapy 11 years prior presented to the emergency room with a non-ST elevation myocardial infarction and was taken for cardiac catheterization followed by three-vessel coronary artery bypass grafting. The LIMA was found to be encased in scar tissue and was deemed unsuitable as a conduit, and a saphenous vein graft was bypassed to the left anterior descending artery in its place. Pathologic review of the LIMA showed nests of tumor cells infiltrating within dense fibrous tissue with areas of necrosis and calcifications consistent with recurrent breast cancer. Interestingly the patients original breast cancer was positive for estrogen receptors (ER) and progesterone receptors (PR) ER and PR and negative for HER2 and she had therefore been treated with 5 years of hormonal therapy. The recurrent cancer found in the LIMA dissection bed at the time of bypass surgery was ER, PR, and HER2 negative, suggesting hormonal therapy driven clonal selection of these metastatic tumor cells. DISCUSSION AND CONCLUSIONS: Scarring in the LIMA dissection bed in patients with a history of cancer and prior chest radiation should be carefully evaluated for the possibility of recurrent cancer. The gross appearance of tissue can be misleading and sending a biopsy for a formal frozen section histologic evaluation should be considered if there is any question of recurrent malignancy.

Impact of mutations in Toll-like receptor pathway genes on esophageal carcinogenesis.

Esophageal adenocarcinoma (EAC) develops in an inflammatory microenvironment with reduced microbial diversity, but mechanisms for these influences remain poorly characterized. We hypothesized that mutations targeting the Toll-like receptor (TLR) pathway could disrupt innate immune signaling and promote a microenvironment that favors tumorigenesis. Through interrogating whole genome sequencing data from 171 EAC patients, we showed that non-synonymous mutations collectively affect the TLR pathway in 25/171 (14.6%, PathScan p = 8.7x10-5) tumors. TLR mutant cases were associated with more proximal tumors and metastatic disease, indicating possible clinical significance of these mutations. Only rare mutations were identified in adjacent Barrett's esophagus samples. We validated our findings in an external EAC dataset with non-synonymous TLR pathway mutations in 33/149 (22.1%, PathScan p = 0.05) tumors, and in other solid tumor types exposed to microbiomes in the COSMIC database (10,318 samples), including uterine endometrioid carcinoma (188/320, 58.8%), cutaneous melanoma (377/988, 38.2%), colorectal adenocarcinoma (402/1519, 26.5%), and stomach adenocarcinoma (151/579, 26.1%). TLR4 was the most frequently mutated gene with eleven mutations in 10/171 (5.8%) of EAC tumors. The TLR4 mutants E439G, S570I, F703C and R787H were confirmed to have impaired reactivity to bacterial lipopolysaccharide with marked reductions in signaling by luciferase reporter assays. Overall, our findings show that TLR pathway genes are recurrently mutated in EAC, and TLR4 mutations have decreased responsiveness to bacterial lipopolysaccharide and may play a role in disease pathogenesis in a subset of patients.