Integrative genomic and transcriptomic profiling of pulmonary sarcomatoid carcinoma identifies molecular subtypes associated with distinct immune features and clinical outcomes.

Background: Pulmonary sarcomatoid carcinoma (PSC) is a rare and aggressive subtype of non-small cell lung cancer (NSCLC), characterized by the presence of epithelial and sarcoma-like components. The molecular and immune landscape of PSC has not been well defined. Methods: Multiomics profiling of 21 pairs of PSCs with matched normal lung tissues was performed through targeted high-depth DNA panel, whole-exome, and RNA sequencing. We describe molecular and immune features that define subgroups of PSC with disparate genomic and immunogenic features as well as distinct clinical outcomes. Results: In total, 27 canonical cancer gene mutations were identified, with TP53 the most frequently mutated gene, followed by KRAS. Interestingly, most TP53 and KRAS mutations were earlier genomic events mapped to the trunks of the tumors, suggesting branching evolution in most PSC tumors. We identified two distinct molecular subtypes of PSC, driven primarily by immune infiltration and signaling. The Immune High (IM-H) subtype was associated with superior survival, highlighting the impact of immune infiltration on the biological and clinical features of localized PSCs. Conclusions: We provided detailed insight into the mutational landscape of PSC and identified two molecular subtypes associated with prognosis. IM-H tumors were associated with favorable recurrence-free survival and overall survival, highlighting the importance of tumor immune infiltration in the biological and clinical features of PSCs.

Thoracic solitary fibrous tumors with small cell features: A clinicopathological and immunohistochemical analysis of 5 cases.

Five cases of thoracic solitary fibrous tumor (SFT) with small cell features are presented mimicking a neuroendocrine neoplasm. The patients were four men and one woman aged 43 to 74 years who presented with symptoms of chest pain, cough, dyspnea or hemoptysis. Two tumors were intrapulmonary neoplasms, while three were pleural-based. Grossly, the tumors ranged in size from 4 to 6 cm and were white and solid; in two tumors necrosis was apparent. Histologically, they were characterized by a cellular proliferation composed of small cells with round nuclei and inconspicuous nucleoli. The cellular proliferation in some areas had a subtle nested pattern, while in other areas the tumor showed extensive sclerosis and small vessel proliferation. Cellular pleomorphism was not marked and the mitotic activity varied from 1 to 5 mitotic figures per 10 high power fields. Microscopically, necrosis was observed in two cases and focally present in one. Immunohistochemical stains showed tumors cells universally negative for pancytokeratin; in the two pulmonary cases, focal staining for synaptophysin, CD56, and INSM1 was observed. The unexpected lack of expression of pancytokeratin led to additional analysis revealing positive staining with CD34 and STAT6 confirming a diagnosis of SFT. Clinical follow-up showed tumor recurrence in one patient while three patients remained alive and well after a period of 12 to 20 months. The current cases highlight an unusual variant of SFT that may be confused with other small cell tumor entities, such as neuroendocrine or neuroectodermal tumors, especially when originating in the thoracic cavity.

Metastatic extraneural glioblastoma diagnosed with molecular testing.

Glioblastoma, the most common malignant brain tumor in adults, is associated with a median overall survival duration of less than 2 years. Extraneural metastases occur in less than 1% of all patients with glioblastoma. The mechanism of extraneural metastasis is unclear. We present a case of extensive extraneural, extraosseous, epidural, and soft-tissue metastasis of glioblastoma. The diagnosis of metastatic glioblastoma was made only after next-generation sequencing (NGS) of the metastatic paraspinal lesions was completed. The CDK4, pTERT, PTEN, and TP53 molecular alterations seen in the initial intracranial glioblastoma were found in the paraspinal tumor, along with the addition of MYC, which is implicated in angiogenesis and epidermal-to-mesenchymal transition. Immunohistochemical stains showed that neoplastic cells were negative for GFAP. In conclusion, this case raises awareness about the role of NGS in the diagnosis of extraneural glioblastoma. This diagnosis was not possible with histology alone and only became evident after molecular profiling of the metastatic lesions and its comparison to the original tumor.

Primary thymic adenoid cystic carcinoma with high-grade transformation: A clinicopathological and immunohistochemical analysis of 4 cases.

Four cases of a distinct carcinoma of the thymic gland are presented. The patients were 4 adult males with an age range from 40 to 47 years (mean, 43.5 years). Clinically, all patients presented with non-specific respiratory symptoms. None of the patients had any prior history of head and neck neoplasm or surgery in that anatomic area. Large anterior mediastinal masses were found on diagnostic imaging with concurrent metastatic disease to pleura, lungs, regional lymph nodes and bones. Microscopically, all tumors were composed of a solid proliferation of hyperchromatic, monomorphic small cells with focal cytoplasmic clearing embedded in a fibromyxoid stroma. In one case, occasional duct-like structures were identified. Immunohistochemically, the tumors were positive for pancytokeratin, CD117 and MYB and negative for myoepithelial markers. Systemic chemotherapy was initiated in all patients. Despite therapy, clinical follow-up revealed that all 4 patients died of their disease 11-23 months after their initial diagnosis. The cases in this series highlight a tumor that is different from conventional thymic carcinoma and that has the morphological and immunohistochemical features commonly seen in adenoid cystic carcinomas with high-grade transformation. Correct diagnosis is essential for patient management.

Uncommon Tumors of the Lung: Recently Described and Rediscovered Tumors.

CONTEXT.­: The great majority of primary pulmonary neoplasms are represented by non-small cell carcinomas-adenocarcinoma and squamous cell carcinoma. In addition, there is another group of neoplasms such as those of neuroendocrine origin that also represent a meaningful subset of primary lung neoplasms. Basically, any other tumor that is not in these groups of tumors may represent an unusual lung neoplasm. OBJECTIVE.­: To highlight more recently described unusual tumoral entities that may represent a challenge in diagnosis and that require awareness of their existence. DATA SOURCES.­: This is a review of 3 different entities: bronchiolar adenoma, adenofibroma, and hemangioblastoma-like clear cell stromal tumor. These tumoral conditions are rare, and a review of the literature is presented. The most relevant morphologic, immunohistochemical, and molecular aspects of bronchiolar adenoma, adenofibroma, and hemangioblastoma-like clear cell stromal tumor are presented. The difficulty of arriving at an unequivocal diagnosis in small biopsies is highlighted. CONCLUSIONS.­: The 3 entities represent uncommon tumors occurring primarily in the lung and a diagnostic challenge not only in biopsy specimens but also often in surgically resected specimens. The use of immunohistochemical stains and in some cases of molecular diagnostics is of aid in arriving at final interpretation.

PAX5 and CD70 are expressed in thymic carcinoma but not in atypical thymoma (WHO type B3 thymoma): an immunohistochemical analysis of 60 cases.

AIMS: Thymic carcinoma and atypical thymoma (WHO type B3 thymoma) are unusual tumours the separation of which may be challenging in small biopsies. Both tumours consist of epithelioid tumour cells that share similar morphology and immunophenotype with conventional markers. Therefore, additional antibodies are needed to differentiate between these tumours. METHODS: For this purpose, a panel of immunohistochemical stains including PAX2, PAX5, PAX8 (all monoclonal) and CD70 was used on whole tumour sections of 30 thymic carcinomas and 30 atypical thymomas to determine the expression pattern of these antibodies. In addition, all tumours were stained with markers that are well known to be expressed in both tumours, including pancytokeratin and cytokeratin 5/6. The percentage of positive tumour cells as well as the intensity of staining were evaluated and scored. RESULTS: PAX5 stained close to 70% of thymic carcinomas while all atypical thymomas were negative for this marker. CD70 was expressed in 18 thymic carcinomas (60%) and in 1 case of atypical thymoma (3%). On the other hand, monoclonal PAX8 was negative in all cases while PAX2 was positive in a single thymic carcinoma. Of the established stains, pancytokeratin and cytokeratin 5/6 were equally positive in both tumours. CONCLUSIONS: Among the markers explored, only PAX5 and CD70 appear to be differentially expressed and are predominantly restricted to thymic carcinomas. Therefore, in small biopsy specimens and in resections in which the morphological features remain equivocal, application of these particular stains may facilitate separation of thymic carcinoma and atypical thymoma.

Primary Pulmonary Carcinomas with Spindle and/or Giant Cell Features: A Review with Emphasis in Classification and Pitfalls in Diagnosis.

Primary carcinomas of the lung are vastly represented by the conventional types of adenocarcinomas or squamous cell carcinomas. However, there are other types of non-small cell carcinomas that although uncommon represent a meaningful group that often pose a problem not only in diagnosis but also in classification. Spindle cell and/or giant cell carcinomas, although uncommon represent an important group of primary lung carcinomas. Important to highlight is that current criteria are rather ambiguous and likely not up to date, which renders the classification of these tumors somewhat more obscure. In addition, with the daily use of immunohistochemical stains, the classification of these tumors may also pose a different problem in the proper allocation of these tumors. Proper classification is highly important in the selection process that takes place using such material for molecular analysis. The current molecular characteristics of these tumors are limited and lack more in-depth studies and analyses that can provide specific targets for the treatment of patients with these tumors. The current review attempts to highlight the shortcomings in the current classification and definitions of these neoplasms as well as the more current view regarding these tumors when the use of immunohistochemical stains is employed.

Basaloid Squamous Cell Carcinomas of the Thymus With Prominent B-Cell Lymphoid Hyperplasia: A Clinicopathologic and Immunohistochemical Study of 10 Cases.

Ten cases of basaloid squamous cell carcinomas of the thymus are presented. The patients are 6 women and 4 men ranging in ages between 51 and 72 years (average: 61.5 y), who presented with nonspecific symptoms of cough, dyspnea, and chest pain with no history of malignancy, myasthenia gravis, or other autoimmune disease. Surgical resection of the mediastinal masses via thoracotomy or sternotomy was performed in all patients. Grossly, the tumors varied in size from 2 to 8 cm, were light tan in color, solid and slightly hemorrhagic, and had infiltrative borders. Histologically, scanning magnification showed elongated interanastomosing ribbons of tumors cells embedded in a lymphoid stroma containing germinal centers. At higher magnification, the tumors cells were round to oval with moderate amounts of lightly eosinophilic cytoplasm, oval nuclei, moderate cellular atypia, and mitotic activity ranging from 3 to 5 mitotic figures per 10 HPFs. In 8 cases, the tumor invaded perithymic adipose tissue, in 1 case the tumor infiltrated pericardium, and in 1 case, the tumor involved the pleura. Immunohistochemical stains showed positive staining in the epithelial component for pancytokeratin, p63, keratin 5/6, and p40, while CD20 and CD79a characterized the lymphoid component. Clinical follow-up was obtained in 7 patients. Two patients died within 24 months and 5 patients remained alive between 12 and 60 months. The current cases highlight the unusual feature of B-cell lymphoid hyperplasia in these tumors and their potential aggressive behavior.

Primary epithelioid hemangioendotheliomas and angiosarcomas of the pleura: a clinicopathological and immunohistochemical analysis of 13 cases.

Thirteen cases of primary epithelioid hemangioendotheliomas (EHE) and epithelioid angiosarcomas (EA) of the pleura are presented. The patients were 7 men and 6 women between the ages of 34 and 65 years (mean: 47 years). The patients presented with non-specific symptoms of cough, dyspnea, and chest pain. Diagnostic imaging revealed the presence of either diffuse pleural thickening or pleural nodules involving the serosal surfaces. Open surgical biopsies were obtained in all cases. Histologically, eight tumors were characterized by the presence of a cellular proliferation composed of medium-sized epithelioid cells embedded in a myxohyaline stroma and a variable spindle cell component. Cellular atypia was mild to moderate and mitotic activity ranged from 1 to 2 per 2 mm2. Immunohistochemical stains for vascular markers, including CAMTA1 were positive, confirming a diagnosis of EHE. Five cases of epithelioid angiosarcomas were characterized by a neoplastic cellular proliferation admixed with areas of necrosis and hemorrhage and characterized by medium-sized epithelioid to spindle-shaped cells with eosinophilic cytoplasm, round to oval nuclei and prominent nucleoli. In addition, marked cytologic atypia and a mitotic activity ranging from 3 to 5 per 2 mm2 were identified. Immunohistochemical studies demonstrated positive staining for vascular markers; however, CAMTA1 was negative. Clinical follow-up obtained in eleven cases showed that all patients had died within 30 months post diagnosis. The current study highlights that even though it may be important to histologically separate EHE from EA for academic purposes, primary pleural origin of these tumors appears to portent an aggressive clinical behavior.

Chromophobe-like carcinoma of the thymus: A clinicopathological and immunohistochemical correlation of 5 cases.

Five cases of primary thymic carcinoma with distinct histopathological features resembling chromophobe carcinomas are presented. The patients were four men and one woman ranging in age between 43 and 72 years. Clinically, the patients presented with non-specific symptoms of dyspnea and chest pain. Diagnostic imaging revealed the presence of anterior mediastinal masses. All patients underwent complete surgical resection of their tumors via thoracotomy. Grossly, the tumors measured between 4.0 and 5.5 cm in greatest diameter and were ill-defined neoplasms with infiltrative borders; they were light brown in color and had a lobulated surface. Areas of hemorrhage and necrosis were not identified. Histologically, all tumors shared similar histopathological features, mainly the presence of infiltrative tumor islands separated by a fibrocollagenous stroma. At higher magnification, the neoplastic cellular proliferation was composed of medium-sized, round to polygonal cells with eosinophilic or granular cytoplasm and a clear perinuclear cytoplasmic halo, which imparted a chromophobe-like appearance. Nuclear atypia and mitotic activity were identified. Histochemical stains for colloidal iron were negative while immunohistochemical stains for pancytokeratin, cytokeratin 5/6, and p40 were positive in all cases, supporting squamous differentiation in these tumors. Clinical follow-up information was obtained in three patients all of whom died between 3 and 5 years after initial diagnosis, while two patients were lost to follow-up. The cellular characteristics of these tumors represent an unusual variant of thymic carcinoma that may pose a diagnostic challenge in small biopsies and that could be easily confused with other primary or metastatic tumors.

Immune cellular patterns of distribution affect outcomes of patients with non-small cell lung cancer.

Studying the cellular geographic distribution in non-small cell lung cancer is essential to understand the roles of cell populations in this type of tumor. In this study, we characterize the spatial cellular distribution of immune cell populations using 23 makers placed in five multiplex immunofluorescence panels and their associations with clinicopathologic variables and outcomes. Our results demonstrate two cellular distribution patterns-an unmixed pattern mostly related to immunoprotective cells and a mixed pattern mostly related to immunosuppressive cells. Distance analysis shows that T-cells expressing immune checkpoints are closer to malignant cells than other cells. Combining the cellular distribution patterns with cellular distances, we can identify four groups related to inflamed and not-inflamed tumors. Cellular distribution patterns and distance are associated with survival in univariate and multivariable analyses. Spatial distribution is a tool to better understand the tumor microenvironment, predict outcomes, and may can help select therapeutic interventions.

Atypical thymoma (epithelial-rich thymoma, well-differentiated thymic carcinoma, WHO type B3 thymoma): A conundrum.

Thymomas composed predominantly of epithelioid tumor cells with scattered lymphocytes have been well recognized in the literature. This subtype of thymoma has been variously termed epithelial-rich thymoma, well-differentiated thymic carcinoma, atypical thymoma, or World Health Organization (WHO) type B3 thymoma. Regardless of the designation however, these tumors are known to show a spectrum of histopathological growth patterns that may pose challenges in interpretation and diagnosis, particularly when dealing with small mediastinoscopic biopsies. Just like any other type of thymoma, those composed predominantly of epithelioid cells may present as encapsulated or invasive tumors. Nevertheless, compared to other subtypes of thymoma, they are uncommon neoplasms. Therefore, it becomes very important to sufficiently sample thymomas before making a diagnosis of a particular subtype, especially when the tumor is rich in epithelioid cells and only has a scant lymphocytic component. Because of the unusual occurrence of these tumors, there are only few large series of cases that attempt to highlight not only the more salient histopathological features but also the most important immunohistochemical and molecular characteristics.

Ligneous brochitis: A clinicopathological correlation of seven cases.

Seven patients with ligneous lesions of the bronchus are presented. The patients are five men and two women between the ages of 51 and 79 years (average: 65) who had prior history of pulmonary non-small cell carcinoma in the past 2-3 years. All the patients had undergone surgical resection followed by chemotherapy. The patients were evaluated for the potential recurrence of carcinoma and bronchial biopsies were obtained. Histologically, all the cases shared similar features, manly the presence of a subepithelial amorphous, acellular, eosinophilic material with minimal inflammatory reaction. Special histochemical stains for micro-organisms were negative as well as congo red for the presence of amyloid. No evidence of malignancy was seen in any of the biopsies. The current cases, represent an unusual histological feature that is more in keeping with ligneous bronchitis, possibly secondary to treatment.

CD70 is a therapeutic target upregulated in EMT-associated EGFR tyrosine kinase inhibitor resistance.

Effective therapeutic strategies are needed for non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations that acquire resistance to EGFR tyrosine kinase inhibitors (TKIs) mediated by epithelial-to-mesenchymal transition (EMT). We investigate cell surface proteins that could be targeted by antibody-based or adoptive cell therapy approaches and identify CD70 as being highly upregulated in EMT-associated resistance. Moreover, CD70 upregulation is an early event in the evolution of resistance and occurs in drug-tolerant persister cells (DTPCs). CD70 promotes cell survival and invasiveness, and stimulation of CD70 triggers signal transduction pathways known to be re-activated with acquired TKI resistance. Anti-CD70 antibody drug conjugates (ADCs) and CD70-targeting chimeric antigen receptor (CAR) T cell and CAR NK cells show potent activity against EGFR TKI-resistant cells and DTPCs. These results identify CD70 as a therapeutic target for EGFR mutant tumors with acquired EGFR TKI resistance that merits clinical investigation.

Analysis of Immune Intratumor Heterogeneity Highlights Immunoregulatory and Coinhibitory Lymphocytes as Hallmarks of Recurrence in Stage I Non-Small Cell Lung Cancer.

Our understanding of the molecular mechanisms underlying postsurgical recurrence of non-small cell lung cancer (NSCLC) is rudimentary. Molecular and T cell repertoire intratumor heterogeneity (ITH) have been reported to be associated with postsurgical relapse; however, how ITH at the cellular level impacts survival is largely unknown. Here we report the analysis of 2880 multispectral images representing 14.2% to 27% of tumor areas from 33 patients with stage I NSCLC, including 17 cases (relapsed within 3 years after surgery) and 16 controls (without recurrence ≥5 years after surgery) using multiplex immunofluorescence. Spatial analysis was conducted to quantify the minimum distance between different cell types and immune cell infiltration around malignant cells. Immune ITH was defined as the variance of immune cells from 3 intratumor regions. We found that tumors from patients having relapsed display different immune biology compared with nonrecurrent tumors, with a higher percentage of tumor cells and macrophages expressing PD-L1 (P =.031 and P =.024, respectively), along with an increase in regulatory T cells (Treg) (P =.018), antigen-experienced T cells (P =.025), and effector-memory T cells (P =.041). Spatial analysis revealed that a higher level of infiltration of PD-L1+ macrophages (CD68+PD-L1+) or antigen-experienced cytotoxic T cells (CD3+CD8+PD-1+) in the tumor was associated with poor overall survival (P =.021 and P =.006, respectively). A higher degree of Treg ITH was associated with inferior recurrence-free survival regardless of tumor mutational burden (P =.022), neoantigen burden (P =.021), genomic ITH (P =.012) and T cell repertoire ITH (P =.001). Using multiregion multiplex immunofluorescence, we characterized ITH at the immune cell level along with whole exome and T cell repertoire sequencing from the same tumor regions. This approach highlights the role of immunoregulatory and coinhibitory signals as well as their spatial distribution and ITH that define the hallmarks of tumor relapse of stage I NSCLC.

Pleural Mesothelioma: Current Practice and Approach.

Pleural mesotheliomas represent one of the most common diagnostic challenges in thoracic pathology. The diagnosis of pleural mesothelioma weighs heavily on clinical and radiologic information. In addition, in the past, before the era of immunohistochemistry, the diagnosis was aided with the use of special histochemical stains-PAS, D-PAS, and mucicarmine, which now very much have been replaced by immunohistochemical stains. In the era of immunohistochemistry, a combination of carcinomatous epitopes and positive mesothelioma markers has become paramount in the diagnosis of mesothelioma, and more recently the use of molecular techniques has become another ancillary tool in supporting such a diagnosis. At the same time, the treatment and clinical outcome of these patients may in some measure be determined by the histopathological features of the tumor and one that also over the years has changed from a palliative type to surgery, chemotherapy, radiotherapy, or a combination of these types. The histopathological growth patterns of mesothelioma are also wide, and in some cases may mimic other tumors that may be primary or metastatic to the pleura. Therefore, the assessment of the diagnosis of mesothelioma is one that requires a global view of the different factors including clinical, radiologic, pathologic-including immunohistochemistry and molecular diagnosis.

Primary mediastinal germ cell tumors.

Mediastinal germ cell tumors share similar histopathological, immunohistochemical, and molecular features with their counterparts in the gonads. Therefore, proper clinical and radiological evaluation of patients with an anterior mediastinal mass becomes essential in the final interpretation of these tumors. The gold standard for the diagnosis of these tumors remains histopathological evaluation. However, immunohistochemical stains and molecular studies also provide an aid in cases in which the histology is not typical. It is also important to keep in mind that a small mediastinoscopic biopsy may not be representative of the entire neoplasm. In this review, we will provide our perspective regarding histopathological diagnosis, staging, immunohistochemical and molecular profile, and briefly family of tumors address pertinent epidemiological, clinical and treatment options. However, the main emphasis is to review the process of pathological assessment in pre and post-treated tumors. Knowledge of the different growth patterns and histological associations is important, mainly when confronted with mediastinoscopic biopsies, which ultimately will determine treatment options.

Stem Cell Theory of Cancer: Origin of Metastasis and Sub-clonality.

Metastasis may be the secret weapon cancer uses to dominate and subjugate, to persist and prevail. However, it is no longer a secret when we realize that a stem cell has the same ways and means to fulfill its own omnipotence and accomplish its own omnipresence… and when we realize that a cancer cell has its own version of stem-ness origin and stem-like nature. In this perspective, we discuss whether stem-ness enables metastasis or mutations drive metastasis. We ponder about low-grade versus high-grade tumors and about primary versus metastatic tumors. We wonder about stochasticity and hierarchy in the genesis and evolution of cancer and of metastasis. We postulate that metastasis may hold the elusive code that makes or breaks a stem-cell versus a genetic theory of cancer. We speculate that the vaunted model of multistep carcinogenesis may be in error and needs some belated remodeling and a major overhaul. We propose that subsequent malignant neoplasms from germ cell tumors and donor-derived malignancies in organ transplants are quintessential experiments of nature and by man that may eventually empower us to elucidate a stem-cell origin of cancer and metastasis. Unfortunately, even the best experiments of cancer and of metastasis will be left unfinished, overlooked, or forgotten, when we do not formulate a proper cancer theory derived from pertinent and illuminating clinical observations. Ultimately, there should be no consternations when we realize that metastasis has a stem-cell rather than a genetic origin, and no reservations when we recognize that metastasis has been providing us some of the most enduring tests and endearing proofs to demonstrate that cancer is indeed a stem-cell rather than a genetic disease after all.