Differential Diagnosis for the 3mm Nodule
- Single most likely diagnosis
- Local recurrence of chromophobe RCC: This is considered the most likely diagnosis due to the history of partial nephrectomy for chromophobe RCC and the appearance of a new nodule in the same region. The fact that the nodule has "matured" and become solid over time, as described by the radiologist, supports this possibility.
- Other Likely diagnoses
- Benign fatty lesion (e.g., lipoma or angiomyolipoma): Although less likely given the history of RCC, benign fatty lesions can occur in this region and may appear as small nodules on imaging.
- Lymph node or lymphatic malformation: The location anterior to the psoas muscle and below the lower pole of the left kidney is also consistent with a lymph node or lymphatic malformation, although this would be less likely given the patient's history.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
- Metastasis from another primary cancer: Although the patient has a history of RCC, it is essential to consider the possibility of metastasis from another primary cancer, as this would significantly alter the management and prognosis.
- Sarcomatoid transformation of RCC: Although the initial pathology did not show sarcomatoid features, it is crucial to consider the possibility of sarcomatoid transformation, as this would indicate a more aggressive disease.
- Rare diagnoses
- Primitive neuroectodermal tumor (PNET) or other soft tissue tumors: These are rare tumors that can occur in the retroperitoneum and may present as small nodules.
- Vascular malformations or aneurysms: Although rare, vascular malformations or aneurysms can occur in this region and may appear as small nodules on imaging.