Primary pulmonary combined scar carcinoma composed of adenocarcinoma, squamous cell carcinoma, and small cell carcinoma: An autopsy case and literature review

Abstract

Primary pulmonary scar carcinoma with triplicate differentiation is very rare. A 66-year-old woman presented with cough, and consulted to a private hospital, where she was pointed out to have abnormal lung shadow by chest X-P. She was admitted to our hospital for scrutiny. Imaging modalities including chest X-P, CT, and MRI revealed a main tumor (35 mm in diameter) in the right lower lobe and multiple small metastases in both lungs. Biopsies and cytology revealed an adenocarcinoma. Metastasis to the liver, iliac bone and tibia bone were also detected. She was diagnosed as stage IV lung adenocarcinoma (T2N3M1), and received chemotherapy. Soon, she complained of right hemiparesis, and brain CT revealed multiple brain metastases. She died of respiratory failure due to bronchopneumonia 7 months after admission. An autopsy revealed a lung tumor (4 × 4 × 3 cm) in the right lower lobe. Miliary micrometastases were recognized in bilateral lungs, brain, bones, pleura, liver, brain, and systemic lymph nodes. The lungs showed bronchopneumonia. The liver was cirrhotic. Microscopically, the primary lung tumor consisted of adenocarcinoma element (70% in area), squamous cell carcinoma element (20%), and small cell carcinoma element (10%), all of which were embedded in a fibroelastic scar with calcification (scar carcinoma). There were gradual merges between the adenocarcinoma and squamous cell carcinoma elements, but the small cell carcinoma element was isolated. The liver metastases were composed only of small cell carcinoma, and other metastatic sites consisted of adenocarcinoma, squamous cell carcinoma, and small cell carcinoma. Other pathologic changes included pulmonary aspergilosis, bronchopneumonia, splenomegaly, emphysema, cardiac hypertrophy, and kidney congestion. The present case shows that a lung scar carcinoma can display triplicate differentiations.