Cytology Detects Endobronchial Metastasis from Appendiceal Signet-Ring Cell Carcinoma in the Absence of Radiographic Lung Masses: A Case Report

Abstract

Introduction/Objective Endobronchial metastasis (EBM) is uncommon, with a reported prevalence of 2% in cases of non-lung primary malignancies. The most frequently observed carcinomas in EBM are from breast, colon, and renal origins. We present a rare case of endobronchial metastasis from a primary tumor of the appendix without lung masses by computed tomography (CT). Methods/Case Report An 83-year-old woman with signet-ring cell carcinoma of the appendix underwent right hemicolectomy and chemotherapy. Two years later, she returned with intractable nausea and vomiting, and respiratory distress. CT of the chest demonstrated diffuse bilateral pulmonary opacities without lung masses. CT of the abdomen showed peritoneal carcinomatosis. Cytology of ascitic fluid displayed metastasis of the patient’s known appendiceal tumor. Bronchoscopy found significant friable debris appearing to be tumor tissue and occluding multiple bronchioles in the right lung. A bronchoalveolar lavage (BAL) specimen from the right lung was sent for liquid-based cytology, which revealed a few atypical cells with eccentric nuclei and intracytoplasmic vacuoles, abundant macrophages, degenerated mixed inflammatory cells, and scattered bronchial epithelial cells. Cell block demonstrated signet-ring cells mimicking macrophages and infiltrating into small fragments of bronchiolar wall. The signet-ring cells were morphologically similar to those found in the ascitic fluid and the patient’s primary tumor, and were highlighted by mucicarmine stain and immunohistochemical stains for CDX-2 and CK20, but not CK7. Results (if a Case Study enter NA) N/A Conclusion Collectively, the findings supported the diagnosis of endobronchial metastasis of signet-ring cell carcinoma from the lower gastrointestinal tract, i.e. the patient’s known appendiceal primary. Our case demonstrates a rare endobronchial metastasis of a primary neoplasm of the appendix, an important diagnostic consideration when evaluating respiratory distress in patients with such cancer histories. We have described the significant role of BAL cytology to uncover endobronchial metastases without lung masses by CT, and illustrated the finding of signet-ring cells mimicking macrophages in a BAL cytology specimen.