Differential Diagnosis for the 3 mm Nodule
- Single most likely diagnosis:
- Fibrosis or scar tissue: The nodule's appearance has "matured" over time, and its density is similar to the psoas muscle, suggesting a benign process. The fact that it was present one month after partial nephrectomy and has remained stable in size also supports this diagnosis.
- Other Likely diagnoses:
- Lymph node: Although no lymph nodes were submitted during the partial nephrectomy, it's possible that this nodule represents a reactive or benign lymph node.
- Granuloma: A small granuloma could present as a 3 mm nodule, although this would be less likely given the patient's history and the nodule's appearance.
- 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-stage, there is always a possibility of metastatic disease, especially in the context of a new nodule. However, the nodule's stable size and benign appearance make this less likely.
- Local recurrence of RCC: Although the nodule is located outside the kidney, it's possible that it represents a local recurrence of the chromophobe RCC. However, the fact that it was present one month after surgery and has remained stable in size makes this less likely.
- Rare diagnoses:
- Sarcoma: A rare possibility, given the patient's history of RCC and the presence of a new nodule. However, the nodule's appearance and stable size make this unlikely.
- Other rare tumors: Such as a paraganglioma or a neurogenic tumor, although these would be extremely rare and unlikely given the patient's history and the nodule's appearance.