Rare cause of large anterior mediastinal mass––Thymolipoma

Background: Among the diverse causes of anterior mediastinal masses, thymolipoma is not a common entity. It largely comprises of adipose tissue and remnants of thymus tissue. Most patients are asymptomatic and are diagnosed incidentally. Case Summary: Sixty-six-year-old female presented to the Emergency Department with a week of worsening shortness of breath, palpitations, diarrhea, palpitations & over 30 kg of unintentional weight loss in the last 1 year. Her investigations were in line of thyrotoxicosis with other lab findings correlating to the disease. However, during investigations, a chest radiograph showed left lower zone opacity and on follow-up CT scan it was revealed to be a huge fatty mass comprising of soft tissues arising from the anterior mediastinum, pushing the left diaphragm inferiorly and the lower lobe of left lung was entirely collapsed. Conclusion: Thymolipoma can occur as a single entity and patients are often clinically asymptomatic. Biopsy is the definitive diagnostic tool, but it can also be challenging, especially if adequate samples are not obtained. CT scan can play an important role in supporting the diagnosis, with findings of fat containing structure arising from the anterior mediastinum along with internal fat stranding & nodularity. Treatment is surgical with excision of the entire mass.