Uncommon Types of Lung Carcinoma With Mixed Histology: Sarcomatoid Carcinoma, Adenosquamous Carcinoma, and Mucoepidermoid Carcinoma

Adenosquamous carcinoma arising within a long-standing intrapulmonary bronchogenic cyst in an adult presenting with hyponatraemia

A 74-year-old woman's persistent hyponatraemia led to the discovery of an adenosquamous carcinoma within an intrapulmonary bronchogenic cyst (IPBC), diagnosed 59 years prior. This is the first reported case of such a transformation in an IPBC. An adenosquamous carcinoma, originating from an intrapulmonary bronchogenic cyst identified 59 years prior, was discovered during the workup for a patient's unexplained, persistent hyponatraemia.

Pulmonary Cytopathology: Current and Future Impact of Microscopy and Immunohistochemistry

With the advancement of tissue procurement techniques, in-depth knowledge of morphology is crucial for cytopathologists to diagnose neoplastic and nonneoplastic lung diseases optimally. Cytopathologists must also be well versed in immunohistochemistry/immunocytochemistry markers and their interpretation for an accurate diagnosis.

Pulmonary squamous cell carcinoma and lymphoepithelial carcinoma - morphology, molecular characteristics and differential diagnosis

Squamous cell carcinoma (SCC) comprises one of the major groups of non-small-cell carcinoma of the lung, and is subtyped into keratinising, non-keratinising and basaloid SCC. SCC can readily be diagnosed using histomorphology alone in keratinising SCC. Confirmatory immunohistochemical analyses should always be applied in non-keratinising and basaloid tumours to exclude differential diagnoses, most prominently adenocarcinoma and high-grade neuroendocrine carcinoma, which may have important therapeutic consequences. According to the World Health Organisation (WHO) classification 2015, the diagnosis of SCC can be rendered in resections of morphologically ambiguous tumours with squamous immunophenotype. In biopsies and cytology preparations in the same setting the current guidelines propose a diagnosis of 'non-small-cell carcinoma, favour SCC' in TTF1-negative and p40-positive tumours to acknowledge a possible sampling bias and restrict extended immunohistochemical evaluation in order to preserve tissue for molecular testing. Most SCC feature a molecular 'tobacco-smoke signature' with enrichment in GG > TT mutations, in line with the strong epidemiological association of SCC with smoking. Targetable mutations are extremely rare but they do occur, in particular in younger and non- or light-smoking patients, warranting molecular investigations. Lymphoepithelial carcinoma (LEC) is a poorly differentiated SCC with a syncytial growth pattern and a usually prominent lymphoplasmacytic infiltrate and frequent Epstein-Barr virus (EBV) association. In this review, we describe the morphological and molecular characteristics of SCC and LEC and discuss the most pertinent differential diagnoses.

Immune checkpoint inhibitors in lung tumors with rare histologies and other thoracic malignancies

In recent years, immunotherapy has significantly changed the treatment of locally advanced/metastatic non-small-cell lung cancer (NSCLC). Conversely, the role of immunotherapy in NSCLC with uncommon histologies remains unclear, while in other rare thoracic malignancies, such as malignant pleural mesothelioma and thymic epithelial tumors, the use of immune checkpoint inhibitors is modifying therapeutic strategies with solid hopes for the future. However, larger prospective studies are urgently needed to define the best treatment strategies and the role of immunotherapy in these orphan tumors. This review provides a comprehensive overview of the emerging role of immunotherapy in the treatment of patients affected by these rare thoracic malignancies.

Case Report: Significant Clinical Benefit From Pemetrexed-Based Therapy in ROS1- and ALK-rearranged Lung Cancer With Adenosquamous Histology

Pemetrexed (used as a platinum doublet or as a maintenance regimen) is an established therapy for patients with advanced non-squamous non-small-cell lung cancer (NSCLC). In addition, certain gene rearrangements (e.g., ALK, ROS1, RET) appear to especially benefit from the use of pemetrexed. Inferior outcomes with pemetrexed compared to other chemotherapies in patients with NSCLC demonstrating squamous histology removed these patients from the labeled indication for the drug. While most squamous cases do not harbor driver oncogenes, rare exceptions exist. Whether the poor outcomes with pemetrexed extend to NSCLC with squamous component harboring driver oncogenes remains unexplored. In this case series, we describe two patients with adenosquamous histology harboring an ROS1 and ALK gene arrangement, respectively, who derived significant benefit from pemetrexed-based therapy. These cases suggest that the value of pemetrexed may need to be re-explored in adenosquamous NSCLC harboring such alterations.

The histologic phenotype of lung cancers is associated with transcriptomic features rather than genomic characteristics

Histology plays an essential role in therapeutic decision-making for lung cancer patients. However, the molecular determinants of lung cancer histology are largely unknown. We conduct whole-exome sequencing and microarray profiling on 19 micro-dissected tumor regions of different histologic subtypes from 9 patients with lung cancers of mixed histology. A median of 68.9% of point mutations and 83% of copy number aberrations are shared between different histologic components within the same tumors. Furthermore, different histologic components within the tumors demonstrate similar subclonal architecture. On the other hand, transcriptomic profiling reveals shared pathways between the same histologic subtypes from different patients, which is supported by the analyses of the transcriptomic data from 141 cell lines and 343 lung cancers of different histologic subtypes. These data derived from mixed histologic subtypes in the setting of identical genetic background and exposure history support that the histologic fate of lung cancer cells is associated with transcriptomic features rather than the genomic profiles in most tumors.

The molecular determinants of lung cancer histologic subtypes are not well understood. Here the authors analyze lung cancers of mixed histology and find that histologic subtypes are associated with transcriptomic features rather than genomic profiles in most tumors.

Immune-Checkpoint Inhibitors in Advanced Non-Small Cell Lung Cancer With Uncommon Histology

BACKGROUND

Immune-checkpoint inhibitors (ICIs) have significantly improved outcome of advanced non-small cell lung cancer (aNSCLC) patients. However, their efficacy remains uncertain in uncommon histologies (UH).

MATERIALS AND METHODS

Data from ICI treated aNSCLC patients (April,2013-January,2021) in one Institution were retrospectively collected. Univariate and multivariate survival analyses were estimated by Kaplan-Meier and Cox proportional hazards regression model, respectively. Objective response rate (ORR) and disease control rate (DCR) were assessed.

RESULTS

Of 375 patients, 79 (21.1%) had UH: 19 (24.1%) sarcomatoid carcinoma, 15 (19.0%) mucinous adenocarcinoma, 10 (12.6%) enteric adenocarcinoma, 8 (10.1%) adenocarcinoma not otherwise specified, 7 (8.9%) large-cell neuroendocrine carcinoma, 6 (7.6%) mixed histology non-adenosquamous, 5 (6.3%) adenosquamous carcinoma, 9 (11.4%) other UH. In UH group, programmed death-ligand 1 (PD-L1) <1%, 1-49%, ≥50% and unknown expression were reported in 27.8%, 22.8%, 31.7% and 17.7% patients respectively and ICI was the second/further-line in the majority of patients. After a median follow-up of 35.64 months (m), median progression-free survival (mPFS) was 2.5 m in UH [95% CI 2.2-2.9 m] versus (vs.) 2.7 m in CH [95% CI 2.3-3.2 m, P-value = .584]; median overall survival (mOS) was 8.8 m [95% CI 4.9-12.6 m] vs. 9.7 m [95% CI 8.0-11.3 m, P-value = .653]. At multivariate analyses only ECOG PS was a confirmed prognostic factor in UH. ORR and DCR were 25.3% and 40.5% in UH vs. 21.6% and 49.5% in CH [P-value = .493 and .155 respectively].

CONCLUSIONS

No significant differences were detected between UH and CH groups. Prospective trials are needed to understand ICIs role in UH population.

Second-line Afatinib or Chemotherapy Following Immunochemotherapy for the Treatment of Metastatic, Squamous Cell Carcinoma of the Lung: Real-world Effectiveness and Safety From a Multisite Retrospective Chart Review in the USA

BACKGROUND

The ErbB family blocker, afatinib, is approved for patients with squamous cell carcinoma (SqCC) of the lung following platinum-doublet chemotherapy but has not been explored following immunochemotherapy. Here, we assessed the characteristics and outcomes of patients with SqCC of the lung who received second-line afatinib or chemotherapy after first-line pembrolizumab plus chemotherapy in a "real-world" setting.

METHODS

In this retrospective, multisite cohort study, community oncologists identified eligible patients and extracted data from electronic health records. Primary outcome measures were patient demographics and clinical characteristics, time on treatment, and incidence of severe immune-related adverse events (irAEs).

RESULTS

Two hundred patients were included: 99 received second-line afatinib and 101 received second-line chemotherapy. Median age was 68 and 66 years, respectively; 35% and 3% of patients had mixed histology tumors, and 39% and 5% of tumors were epidermal growth factor receptor (EGFR) mutation-positive (EGFRm⁺). Median time on treatment was 7.3 months with afatinib (mixed histology/SqCC tumors: 8.1/5.8 months; EGFRm⁺/EGFRm^- tumors: 7.4/5.9 months) and 4.2 months with chemotherapy. Grade 3/4 irAEs were observed in 6 patients in the afatinib cohort (all had a prior grade 3/4 irAE during first-line therapy) and no patients in the chemotherapy cohort. The most common adverse drug reactions with afatinib were diarrhea (26%), rash (6%), stomatitis, fatigue, and nausea (5% each).

CONCLUSION

Encouraging time on treatment, and absence of newly diagnosed irAEs, indicate that afatinib is a treatment option following immunochemotherapy in patients with SqCC of the lung, and is currently the only approved oral agent in this setting.

Dyspnea, focal wheeze, and a slow growing endobronchial tumor

We describe a case of an otherwise healthy woman who presented with nonspecific respiratory symptoms, but was found to have recurrent focal findings on chest radiograph. Her CT scan showed an endobronchial lesion with distal bronchiectasis which was ultimately diagnosed as a mucoepidermoid carcinoma. In this report we discuss the clinical, radiographic, bronchoscopic and pathologic findings of rarely seen endobronchial mucoepidermoid tumors.

Targeted Therapy and Checkpoint Immunotherapy in Lung Cancer

Lung cancer is the leading cause of cancer mortality. It is classified into different histologic subtypes, including adenocarcinoma, squamous carcinoma, and large cell carcinoma (commonly referred as non-small cell lung cancer) and small cell lung cancer. Comprehensive molecular characterization of lung cancer has expanded our understanding of the cellular origins and molecular pathways affected in each of these subtypes. Many of these genetic alterations represent potential therapeutic targets for which drugs are constantly under development. This article discusses the molecular characteristics of the main lung cancer subtypes and discusses the current guidelines and novel targeted therapies, including checkpoint immunotherapy.

An Uncommon Lung Neoplasm in a Young Patient: Diagnostic Challenges

Patient: Female, 29-year-old

Final Diagnosis: Lung adenosquamous carcinoma

Symptoms: Cough • Low back pain • night sweats • thoracic pain • weight loss

Medication: —

Clinical Procedure: Chemotherapy • CT-scan • fiberoptic bronchoscopy • radiotherapy • transbronchial biopsy

Specialty: Oncology • Pulmonology

A 38-Year-Old Man With An Ataxic Gait, Night Sweats, and Weight Loss

CASE PRESENTATION

A 38-year-old Jamaican man with no medical history presented with worsening right-sided weakness. He developed an ascending hemiparesis that began in the right lower extremity 3 months ago and progressed to the right upper extremity this past month. Over the past 3 months, the patient has had unintentional weight loss and an ataxic gait, and for the past month he has had night sweats. He denied headache, vision changes, numbness, tingling, cough, or chest pain. Social history was significant for 20 smoking pack-years and daily use of marijuana.

Initial Experience with Hybrid Argon Plasma Coagulation as a Novel Local Treatment Method for Tracheobronchial Mucoepidermoid Carcinoma

Tracheobronchial mucoepidermoid carcinoma (MEC) is a type of salivary gland tumor. Surgical resection is the main treatment for MEC, but it is associated with risks. Hybrid argon plasma coagulation (HybridAPC®) is an innovative technique combining APC with a water cushion function which can be used for the treatment of MEC. We aimed to evaluate the efficacy and safety of HybridAPC for MEC in 2 patients diagnosed with MEC based on histological examination of biopsies. Full preoperative assessments were done by white-light bronchoscopy, autofluorescence imaging, narrow-band imaging, and radial probe endobronchial ultrasound. HybridAPC was administered after these evaluations. Both patients were followed up for more than 3 months. HybridAPC ablation was completed successfully, with no complications. HybridAPC thus appears to be a safe and efficient treatment for MEC.

The importance of EGFR mutation testing in squamous cell carcinoma or non-small cell carcinoma favor squamous cell carcinoma diagnosed from small lung biopsies

Background

Adenosquamous carcinoma (ADSC) of the lung, a rare but aggressive subtype of non-small cell lung cancer (NSCLC), is defined as a carcinoma containing components of adenocarcinoma (ADC) and squamous cell carcinoma (SqCC). Mutations of epidermal growth factor receptor (EGFR) are found at a frequency of 15 to 44% in Asian ADSC, and EGFR tyrosine kinase inhibitors (EGFR-TKIs) are a more effective treatment for EGFR-mutated ADSC compared to chemotherapy. However, ADSC in small lung biopsies could be misdiagnosed as SqCC or non-small cell carcinoma (NSCC) favor SqCC due to undersampling, which may result in neglecting of EGFR mutation testing and affecting patients’ clinical management, particularly in Asian patients that relatively have high prevalence of EGFR mutation.

Methods

A total of 148 small lung biopsy cases with pathological diagnosis of SqCC or NSCC favor SqCC were retrospectively enrolled. The frequency of EGFR mutations and the correlation between patients’ EGFR mutation status and clinicopathological characteristics were evaluated.

Results

EGFR mutations were found in 8.8% (13 /148) of all cases with 5.2% (7/135) in SqCC and 46.2% (6/13) in NSCC favor SqCC. There were 7 (53.8%) L858R mutation, 4 (30.8%) exon 19 deletions, and 2 (15.4%) cases with coexistent L858R and T790 M mutations. Multivariate analysis showed that EGFR mutations were more prevalent in never-smokers (83.3% versus 16.7%, p = 0.006) and patients diagnosed as NSCC favor SqCC (46.2% versus 5.2%, p = 0.001). Moreover, 75% (3/4) of EGFR mutation-positive cases with subsequent surgical resection or rebiopsy were further diagnosed as ADSC.

Conclusions

EGFR mutation testing should be performed in Asian patients with SqCC diagnosed from small lung biopsies, especially in never-smokers and patients with diagnosis of NSCC favor SqCC, which have a high probability of being ADSC.

Whole transcriptome targeted gene quantification provides new insights on pulmonary sarcomatoid carcinomas

Pulmonary sarcomatoid carcinomas (PSC) are a rare group of lung cancer with a median overall survival of 9–12 months. PSC are divided into five histotypes, challenging to diagnose and treat. The identification of PSC biomarkers is warranted, but PSC molecular profile remains to be defined. Herein, a targeted whole transcriptome analysis was performed on 14 PSC samples, evaluated also for the presence of the main oncogene mutations and rearrangements. PSC expression data were compared with transcriptome data of lung adenocarcinomas (LUAD) and squamous cell carcinomas (LUSC) from The Cancer Genome Atlas. Deregulated genes were used for pathway enrichment analysis; the most representative genes were tested by immunohistochemistry (IHC) in an independent cohort (30 PSC, 31 LUAD, 31 LUSC). All PSC cases were investigated for PD-L1 expression. Thirty-eight genes deregulated in PSC were identified, among these IGJ and SLMAP were confirmed by IHC. Moreover, Forkhead box signaling and Fanconi anemia pathways were specifically enriched in PSC. Finally, some PSC harboured alterations in genes targetable by tyrosine kinase inhibitors, as EGFR and MET. We provide a deep molecular characterization of PSC; the identification of specific molecular profiles, besides increasing our knowledge on PSC biology, might suggest new strategies to improve patients management.