Indiana University Indianapolis, IN, United States
Rawan Aljaras, MD, Bianca Puello, MD, Mohammad Al-Haddad, MD Indiana University, Indianapolis, IN
Introduction: Thymomas are interesting, rare tumors, with a unique association with para-neoplastic syndromes, in particular myasthenia gravis. The majority of thymomas are encapsulated masses and exhibit a benign behavior. Less frequently, thymomas may be locally invasive, or rarely, they may metastasize to distant sites. In this interesting case, we are highlighting an extremely unusual behavior of a thymoma, which metastasized to the pancreas.
Case Description/Methods: This is a report of a 45 year old male patient, who was initially diagnosed with thymoma in 2014, after complaints of light-headedness. Work up included a chest x-ray, that showed an anterior mediastinal mass. He underwent video-assisted thoracoscopic surgery with complete resection of the disease, followed by chemotherapy and radiotherapy. Pathology showed a WHO type AB thymoma. The patient was diagnosed with two intra-thoracic recurrences in the subsequent 3 years, also treated with surgical resection. Most recently, he presented for regular follow up, when he was incidentally found to have a pancreatic head mass on CT imaging, highly suspicious for a primary pancreatic tumor. Endoscopic ultrasound guided fine needle biopsy confirmed metastatic thymoma.
Discussion: The overall incidence of thymoma in the US is 0.13 per 100,000 person-year. Thymomas account for about 20 percent of mediastinal neoplasms, but no more than 1% of all malignancies. Metastases develop in up to 20% of thymoma patients, with intra-abdominal recurrences and pancreatic metastases being very uncommon manifestations. The most frequently reported sites of thymoma metastases are lymph nodes and pleura. Providers in this particular case were almost all in agreement on a high likelihood of a second primary malignancy, rather than metastasis, upon initial evaluation of the radiologic findings of the pancreatic mass, based on literature review and their own clinical experience. While several studies based at single treatment centers have suggested that thymoma patients have a broadly increased risk for other malignancies, follow up data from US cancer registries support a more limited spectrum of cancer risk. In this case, we purpose a consideration for metastatic disease upon evaluation of a thymoma patient presenting for regular surveillance, or with symptoms concerning for abdominal pathology. It is extremely rare, but still a possibility.
Figure: A- CT chest with IV contrast, showing a 3.1*3.0 cm mass in the head of pancreas. B- Thymoma (Fine-Needle Aspiration). Smear revels clusters of cohesive spindled to epithelioid cells with prominent nucleoli and minimal pleomorphism, admixed with lymphocytes. C- Thymoma (Cell Block). The cell block demonstrates similar features found within the smear. There are cohesive groups of spindled to epithelioid cells interspersed with lymphocytes.
Rawan Aljaras indicated no relevant financial relationships.
Bianca Puello indicated no relevant financial relationships.
Mohammad Al-Haddad indicated no relevant financial relationships.
Rawan Aljaras, MD, Bianca Puello, MD, Mohammad Al-Haddad, MD. P2162 - Pancreatic Metastasis Originating From a Thymoma, A Report of an Extremely Rare Case, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.