Differential Diagnosis for the 3mm Nodular Finding
- Single most likely diagnosis:
- Surgical clip or artifact: Given that the 3mm nodular finding has been present since 1 month after partial nephrectomy and has "matured" over time, it is likely a benign finding related to the previous surgery, such as a surgical clip or an artifact from the surgical procedure.
- Other Likely diagnoses:
- Fibrotic nodule: A small area of fibrosis in the fat anterior to the psoas muscle, which could be a result of the previous surgery or a benign process.
- Lymph node: Although the size is small, it could be a normal lymph node that has been present and stable over time.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Metastatic disease: Although the primary tumor was small (1.3 cm) and of a relatively indolent type (chromophobe RCC), it is essential to consider the possibility of metastatic disease, especially in the context of a new finding.
- Local recurrence: Although the 1.5 cm mass in the perinephric space was biopsied and found to be benign, it is crucial to consider the possibility of local recurrence of the primary tumor.
- Rare diagnoses:
- Primary soft tissue tumor: A rare possibility, such as a lipoma, hemangioma, or other benign soft tissue tumor, although these are unlikely given the patient's history and the stable nature of the finding.
- Inflammatory or infectious process: A rare possibility, such as a granuloma or an abscess, although these are unlikely given the patient's history and the stable nature of the finding.
Given the information provided, the 3mm nodular finding is likely benign, and the most probable explanation is a surgical clip or artifact. However, it is essential to continue monitoring the patient with regular imaging to ensure that the finding remains stable and does not change over time.