Differential Diagnosis for a 4 cm Left Upper Pole Solid Mass in a 54 yo Woman with Stage 4 CKD

Single Most Likely Diagnosis

• Renal Cell Carcinoma (RCC): Given the patient's age, sex, and the presence of a solid mass in the kidney, RCC is a leading consideration. The incidence of RCC increases with age, and it is more common in women. Stage 4 Chronic Kidney Disease (CKD) may also increase the risk for RCC due to chronic inflammation and potential underlying genetic predispositions.

Other Likely Diagnoses

• Angiomyolipoma (AML): AMLs are benign tumors of the kidney that can grow large enough to cause symptoms or be detected incidentally. They are more common in women and can be associated with tuberous sclerosis complex, though most are sporadic. The presence of a solid mass, especially if it contains fat (which can be detected on imaging), would support this diagnosis.
• Onocytoma: Onocytomas are benign renal tumors that can mimic RCC in appearance and symptoms. They are typically solid and can grow to significant sizes. While less common than RCC, they are an important consideration in the differential diagnosis of a renal mass.

Do Not Miss Diagnoses

• Metastasis to the Kidney: Although less common than primary renal tumors, metastases to the kidney from other primary cancers (e.g., lung, breast, melanoma) can occur and would significantly alter management. Given the patient's age and sex, a thorough history and evaluation for other primary malignancies are crucial.
• Lymphoma Involving the Kidney: Renal involvement by lymphoma, either primary or secondary, is rare but can present as a solid mass. This diagnosis is critical to consider due to its implications for treatment and prognosis.

Rare Diagnoses

• Juxtaglomerular Cell Tumor: A rare, usually benign tumor that can cause hypertension due to renin secretion. It is more common in younger individuals but should be considered in the differential diagnosis of a renal mass.
• Renal Leiomyoma: A rare, benign smooth muscle tumor of the kidney. While uncommon, it can present as a solid renal mass and should be considered, especially if imaging characteristics are suggestive.
• Solitary Fibrous Tumor of the Kidney: A rare tumor that can be benign or malignant. It is uncommon in the kidney but can present as a solid mass, making it a consideration in the differential diagnosis.