Differential Diagnosis for the 3 mm Nodule
- Single most likely diagnosis
- Fat necrosis or a benign post-surgical change: This is the most likely diagnosis given the nodule's small size, location, and the fact that it has been present since one month after the partial nephrectomy. The radiologist's description of it as having "matured" over time also suggests a benign process.
- Other Likely diagnoses
- Post-surgical granuloma: This is a possible diagnosis given the nodule's location near the surgical site and its appearance on imaging. However, the fact that it has been stable for three years makes this less likely.
- Reactive lymph node: Although the nodule is small, it could potentially be a reactive lymph node responding to the surgical trauma. However, its location in the fat anterior to the psoas muscle makes this less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Metastatic disease: Although the primary tumor was small and low-grade, there is always a possibility of metastatic disease, especially in the context of a new nodule appearing after surgery. However, the fact that the nodule has been stable for three years and is very small makes this less likely.
- Local recurrence of RCC: This is another "do not miss" diagnosis, although the fact that the nodule is located outside of the kidney and has been present since shortly after surgery makes this less likely.
- Rare diagnoses
- Soft tissue sarcoma: This is a rare but possible diagnosis, although the fact that the nodule is small and has been stable for three years makes this unlikely.
- Other rare benign tumors (e.g. lipoma, hemangioma): These are possible but rare diagnoses, and the fact that the nodule has been present since shortly after surgery makes them less likely.