INTRODUCTION: Sarcomatoid mesothelioma is a rare and aggressive subtype of malignant pleural mesothelioma accounting for only 10% of all cases. It typically presents with extrapulmonary metastases with an average survival rate of 6 months from time of diagnosis and 3.5 months for the desmoplastic mesothelioma subtype (1) . We report an atypical presentation where the tumor was caught on screening low dose CT scan at an initial stage while the patient was still asymptomatic.
CASE PRESENTATION:Patient is a 71-year-old female with past medical history significant for Hashimoto's thyroiditis, myocardial infarction, stroke, current smoker (56-pack-year history) who underwent lung cancer screening with low-dose CT scan. She was noted to have a right lower lobe lesion with smooth margins abutting the right hemidiaphragm, measuring 1.9 x 1.8x 1.4 cm. It was classified as lung RADS 1.1 category 4A. Whole body pet CT showed mild hypermetabolic activity within the lesion with a max SUV of 2.6 housenfield units without evidence of nodal involvement. CT-guided biopsy was attempted and was unsuccessful given the location and significant diaphragmatic movement. She was evaluated by cardiothoracic surgery who recommended video assisted thoracoscopic surgical resection. Mass resection involving diaphragmatic and lung wedge resection was successfully performed with confirmed negative margins. A minimum diaphragm defect was closed with staples. The hospital course was complicated with minimal right apical pneumothorax after chest tube removal which was resolving on the day of discharge. During follow-up, the cancer was staged as 1B. Biopsy results revealed high-grade sarcomatoid mesothelioma with extensive desmoplastic morphology, pathology was unable to rule out sarcomatoid carcinoma due to nonspecific immunohistochemical findings. The case was discussed at tumor board and plans were to proceed with chemotherapy with cisplatin & pemetrexed followed by radiation therapy. The patient is currently undergoing chemotherapy.DISCUSSION: Sarcomatoid neoplasmas have a poor prognosis and are usually diagnosed once the cancer has already metastasized. In our case the screening low dose CT scan proved to be valuable as the tumor was caught at an early stage and resected prior to any metastasis. Given the rare nature of the tumor, we hope that the information provided can add to the few other case reports for better understanding of this cancer.CONCLUSIONS: This case highlights the significance of relying on radiographic evidence such as low dose CT scan for early diagnosis of potentially life-threatening illnesses. Recent guideline changes now recommend screening to begin at age 50 years for adults who have a 20 pack-year smoking history and current smokers (2). As providers, we should continue to encourage our patients to undergo lung cancer screening with low-dose CT scan to improve prognosis of common as well as rare tumors.
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