P1965 - A Rare Presentation of Synchronous Primary Pulmonary and Cecal Adenocarcinoma

Maryana Stryelkina, DO, Alexis Bejcek, MD, Niket Sonpal, MD
Baylor Scott & White Medical Center, Temple, TX

Introduction: Colorectal cancer is the third most common cancer worldwide. Approximately 25-30% of individuals diagnosed with CRC present with distant metastasis, the lung being the most common extra-abdominal site. About 10% of pulmonary metastasis will present as a single pulmonary nodule. Rarely, in patients with current or pre-existing CRC, synchronous primary lung cancer can present as a solitary pulmonary nodule. Our study describes a rare case of synchronous adenocarcinoma of the colon and lung.



Case Description/Methods: A 58-year-old male was admitted for symptomatic iron deficiency anemia. A diagnostic colonoscopy revealed a 5 cm ulcerated cecal mass, confirmed as moderately differentiated adenocarcinoma. Biopsy confirmed moderately differentiated adenocarcinoma. Abdominal CT showed a 6.2 x 5.5 cm cecal mass with appendiceal obstruction, and chest CT identified a 1.2 cm right lung nodule. CT-guided biopsy of the lung nodule confirmed primary adenocarcinoma, TTF1 and CK7 positive, CK20 negative. Serum CEA was normal at 2.4 ng/mL. The patient underwent right hemicolectomy for the cecal adenocarcinoma, revealing a 7.8 cm mass with mucinous features, pT3N0. A lower right lobectomy confirmed lung adenocarcinoma with EGFR mutation in exon 19, BRAF and KRAS negative. After a complete workup, the final diagnosis was primary adenocarcinoma of the colon with synchronous primary lung adenocarcinoma. Post-radical resection, the patient remained cancer-free for over two years until presenting with acute periumbilical pain. CT scan revealed a small bowel mass, which was surgically excised. Pathology confirmed a third primary malignancy: invasive, moderately differentiated small intestinal adenocarcinoma, positive for CK20, CDX2, and SATB-2. The patient is undergoing adjuvant chemotherapy and remains cancer-free.



Discussion: Solitary pulmonary nodules are typically described in the literature as pulmonary metastases in colorectal cancer patients. Diagnosing two different adenocarcinomas simultaneously is rare, and the distinction from metastatic disease is vital for determining appropriate treatment. This case highlights the importance of thorough staging and tissue sampling to differentiate synchronous cancers from colorectal cancer with pulmonary metastases effectively.




Disclosures:


Maryana Stryelkina, DO, Alexis Bejcek, MD, Niket Sonpal, MD. P1965 - A Rare Presentation of Synchronous Primary Pulmonary and Cecal Adenocarcinoma, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.