Image Quizzes

Dry cough and dyspnea

Reviewed by Karl J. D'Silva, MD

NIGEL DOWNER/Science Source

A 58-year-old man with a 20-year–pack history of smoking initially presented with a persistent dry cough and dyspnea. Clubbing was noted on physical examination and breath sounds in the right upper lung were weak. Other than hypertension, which the patient manages with angiotensin-converting enzyme (ACE) inhibitors, medical history is unremarkable. The patient notes that this medication has always made him cough, but dyspnea has only developed over the past 6 weeks. Respiratory symptoms prompted a chest radiograph which revealed a mass in the upper lobe of the right lung. Transbronchial lung biopsy of the right lung reveals components of adenocarcinoma; the specimen is otherwise squamous.

What is the likely diagnosis?

Adenocarcinoma

Squamous cell carcinoma

Adenosquamous carcinoma

Large cell carcinoma

Based on the patient's presentation and workup, the likely diagnosis is adenosquamous carcinoma of the lung, a relatively rare subtype of non–small cell lung cancer (NSCLC). Adenosquamous carcinoma displays qualities of both squamous cell carcinoma and adenocarcinoma; for definitive diagnosis, the cancer must contain 10% of each of these major NSCLC subtypes. Maeda and colleagues concluded that adenosquamous carcinoma occurs more frequently among men and that the age at the time of diagnosis is higher among such cancers compared with adenocarcinoma. Several studies have confirmed that adenosquamous carcinoma of the lung is also more prevalent among smokers.

Though a diagnosis of adenosquamous carcinoma may be suspected after small biopsies, cytology, or excisional biopsies, definitive diagnosis necessitates a resection specimen. If any adenocarcinoma component is observed in a biopsy specimen that is otherwise squamous, as in the present case, this finding is an indication for molecular testing. Epidermal growth factor receptor (EGFR) mutations may be present in adenosquamous carcinoma cancers, despite a majority of cancers with EGFR mutations being among nonsmokers or former light smokers with adenocarcinoma histology. In addition, even for patients diagnosed with squamous cell carcinoma, adenosquamous carcinoma should be considered if genetic testing suggests EGFR mutations.

Relative to adenocarcinoma and squamous cell carcinoma, adenosquamous carcinoma has higher grade malignancy, more advanced postoperative stage, and stronger lymph nodal invasiveness. In terms of treatment, surgical resection is the curative option for adenosquamous carcinoma of the lung, with lobectomy with lymphadenectomy considered for first-line treatment. Though the most beneficial chemotherapy regimen for patients with adenosquamous carcinoma of the lung remains the subject of investigation, platinum-based doublet chemotherapy is the current standard treatment option. EGFR tyrosine kinase inhibitors may be an effective option for EGFR-positive patients.

Karl J. D'Silva, MD, Clinical Assistant Professor, Department of Medicine, Tufts University School of Medicine, Boston; Medical Director, Department of Oncology and Hematology, Lahey Hospital and Medical Center, Peabody, Massachusetts.

Karl J. D'Silva, MD, has disclosed no relevant financial relationships.

Image Quizzes are fictional or fictionalized clinical scenarios intended to provide evidence-based educational takeaways.

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