Melanoma of unknown primary (MUP) with endobronchial involvement is a rare diagnostic presentation that may clinically and radiologically mimic primary lung cancer. We report the case of a 46-year-old man, a chronic smoker with a 20-pack-year history and a previous excisional biopsy of an atypical scalp nevus, who presented with low-volume hemoptysis and constitutional decline evolving over three months. Chest imaging revealed a large necrotic mass involving the right middle and lower lobes, associated with bilateral pulmonary nodules in a cannonball pattern and mediastinal lymphadenopathy, initially suggesting an advanced primary lung malignancy. Bronchoscopy demonstrated an obstructing endobronchial lesion at the level of the bronchus intermedius. Histopathological examination revealed a malignant melanocytic proliferation, with immunohistochemistry showing positivity for melanoma antigen recognized by T cells 1 (Melan-A) and human melanoma black 45 (HMB-45) and negativity for thyroid transcription factor-1 (TTF-1), cytokeratin AE1/AE3 (AE1/AE3), and p40, supporting the diagnosis of malignant melanoma. Extensive evaluation for an extrathoracic primary, including complete dermatological and mucosal examination and fundoscopy, failed to identify a primary lesion. Staging revealed additional brain, peritoneal, and bone involvement at diagnosis. Primary pulmonary melanoma and MUP with endobronchial involvement were considered, with the overall clinical and pathological findings favoring the latter diagnosis. The case was discussed at a multidisciplinary tumor board, and systemic immunotherapy was initiated. This case highlights the diagnostic challenge posed by an endobronchial melanocytic lesion in a patient with a smoking history and emphasizes the importance of a thorough search for an extrathoracic primary before diagnosing primary pulmonary melanoma.

Pulmonary dirofilariasis is a relatively rare zoonotic infection caused by Dirofilaria immitis, which often presents as pulmonary nodules mimicking primary lung cancer or metastatic disease on imaging. Herein, we report two cases of pulmonary dirofilariasis diagnosed using video-assisted thoracoscopic wedge resection. A man in his 60s with an 8-mm solitary pulmonary nodule and a woman in her 70s with multiple pulmonary nodules detected during follow-up after endoscopic submucosal dissection for intramucosal colorectal cancer underwent thoracoscopic wedge resection because malignancy could not be excluded. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) demonstrated only mild or absent fluorodeoxyglucose uptake in the lesions. Histopathological examination revealed cross sections of D. immitis within the pulmonary arteries, confirming the diagnosis of pulmonary dirofilariasis in both cases. As pulmonary dirofilariasis closely resembles malignant pulmonary lesions on imaging, preoperative diagnosis remains difficult. Accordingly, this disease should be included in the differential diagnosis of solitary and multiple pulmonary nodules. Video-assisted thoracoscopic wedge resection provides a valuable approach as it provides definitive diagnosis and curative treatment.

Clonal haematopoiesis is a precursor of myeloid neoplasia and common in older adults, Precursor risk stratification is critical to early cancer detection, guiding surveillance and prevention efforts to high-risk populations. Existing clonal haematopoiesis risk scores use molecular features to estimate risk of myeloid neoplasia, but only around 1% of adults with detectable clonal haematopoiesis are at high risk of myeloid neoplasia transformation. Moreover, sequencing based molecular diagnostics are expensive with limited global availability highlighting the need for pre-sequencing strategies which identify populations enriched for individuals with high-risk clonal haematopoiesis.

Immune checkpoint inhibitors (ICIs) have significantly improved outcomes in advanced non-small cell lung cancer (NSCLC) but may induce immune-related adverse events (irAEs), including hypophysitis. Although endocrine irAEs usually present with nonspecific constitutional symptoms, atypical manifestations may delay diagnosis and expose patients to unnecessary invasive procedures. We report the case of a 76-year-old man with metastatic NSCLC receiving first-line nivolumab, ipilimumab, carboplatin, and pemetrexed who developed profound asthenia, altered mental status, bilious vomiting, and severe gastrointestinal dilation suggestive of acute mechanical bowel obstruction after two treatment cycles. Computed tomography demonstrated marked gastric and intestinal distension, and surgical management was initially considered. Endocrine evaluation subsequently revealed central hypothyroidism and secondary adrenal insufficiency, consistent with ICI-induced hypophysitis. Prompt initiation of physiological hormone replacement with intravenous hydrocortisone followed by thyroid hormone supplementation resulted in rapid neurological and systemic recovery, complete restoration of gastrointestinal motility, radiological resolution of bowel dilatation, and avoidance of surgery. Follow-up imaging also demonstrated a partial tumor response, which has remained durable for more than two years without additional anticancer treatment while the patient continues long-term endocrine replacement therapy. This case expands the clinical spectrum of ICI-induced hypophysitis by describing an unusual presentation as acute paralytic ileus mimicking mechanical bowel obstruction. It underscores the importance of maintaining a high index of suspicion for endocrine irAEs in patients receiving ICIs who develop unexplained multisystem deterioration or apparent surgical abdomen. Early hormonal assessment and timely replacement therapy can be lifesaving, prevent unnecessary surgical interventions, and allow optimal multidisciplinary management without compromising oncologic outcomes.