Differential Diagnosis for 3mm Nodule
- Single most likely diagnosis
- Post-surgical granuloma or scar: This is the most likely diagnosis given the nodule's appearance after surgery and its maturation over time. The location in the fat anterior to the psoas, a common site for surgical trauma, further supports this diagnosis.
- Other Likely diagnoses
- Lipoma or other benign fat lesion: The nodule's small size and location in the fat suggest a benign lesion such as a lipoma. However, the fact that it was not present before surgery and appeared afterwards makes this less likely.
- Reactive lymph node: Although less common in this location, a reactive lymph node could be considered, especially given the recent surgical history.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Metastasis from the chromophobe RCC: Although the primary tumor was small (T1a) and of a relatively favorable histology, metastasis to the fat or soft tissues is a possibility that should not be overlooked.
- Recurrence of chromophobe RCC: Local recurrence, although less likely given the small size of the primary tumor and the time frame, is a critical diagnosis not to miss.
- Rare diagnoses
- Soft tissue sarcoma: This would be an unusual occurrence, especially in the context of recent surgery, but it is a diagnosis that should be considered in the differential due to its potential severity.
- Other rare soft tissue tumors (e.g., schwannoma, neurofibroma): These are less likely but should be kept in mind, especially if the nodule's characteristics do not fit more common diagnoses.