Differential Diagnosis
- Single most likely diagnosis
- Residual thymic tissue: The CT findings of a soft tissue density within the upper anterior mediastinum, described as suggesting residual thymic tissue, aligns with this diagnosis. The presence of non-specific bilateral axillary lymph nodes does not strongly indicate an alternative diagnosis, and the trace pericardial fluid and normal heart size do not point towards an acute cardiac issue.
- Other Likely diagnoses
- Reactive lymphadenopathy: The non-specific bilateral axillary lymph nodes could be reactive, which is a common and benign condition. This could be in response to a variety of stimuli, including infection or inflammation.
- Benign mediastinal cyst: Although the description suggests residual thymic tissue, a benign mediastinal cyst could also present as a soft tissue density in the anterior mediastinum.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Lymphoma: While the non-specific lymph nodes might not strongly suggest lymphoma, it is a critical diagnosis not to miss due to its significant implications for treatment and prognosis.
- Thymoma: Although less common, thymoma could present with a mass in the anterior mediastinum. Given the potential for thymoma to be associated with myasthenia gravis and other paraneoplastic syndromes, it is crucial to consider.
- Metastatic disease: The presence of lymph nodes and a mediastinal mass could potentially indicate metastatic disease from another primary site, which would significantly alter management.
- Rare diagnoses
- Germ cell tumor: These tumors can occur in the mediastinum and might present with a similar appearance on CT.
- Castleman disease: A rare lymphoproliferative disorder that can present with lymphadenopathy and a mediastinal mass.
- Mediastinal sarcoma: A rare tumor that could present as a soft tissue mass in the mediastinum.