Primary Malignant Melanoma of Renal Pelvis with Extensive Clear Cell Change

Renal Metastatic Melanoma Presenting With Solitary Mass

The kidney is a rare site of metastatic implantation. Metastases to the kidney most commonly originate from carcinomas in the lungs, breasts, and colon. Melanoma metastasis to the kidney is rare. We present an unusual case of melanoma metastasis to the kidney arising in a 76-year-old male who was diagnosed with melanoma two years ago. We emphasize the importance of thorough patient anamnesis when diagnosing renal cell carcinoma or urothelial carcinoma is challenging. In cases where patients with a history of melanoma present with new masses or lesions, even in atypical areas, considering melanoma metastasis in the differential diagnosis is crucial.

The Differential Diagnosis of Medullary-Based Renal Masses

CONTEXT.—

Renal malignancies can be divided into cortical- and medullary-based tumors, the latter of which classically infiltrate the renal parenchyma by extending between nonneoplastic structures. Although high-grade cortical tumors can rarely exhibit the same growth pattern, the infiltrative morphology should elicit a differential diagnosis to be considered in each case. However, these diagnoses can be challenging to distinguish, especially on small renal biopsy samples.

OBJECTIVE.—

To provide an overview of the clinical, gross, and microscopic findings; genetic and molecular alterations; and immunohistochemical evaluation of medullary-based renal tumors and other tumor types with overlapping morphologies and growth patterns.

DATA SOURCES.—

Literature review and personal observations were used to compile the information in this review.

CONCLUSIONS.—

Collecting duct carcinoma is a prototypical medullary-based tumor, and although diagnostic criteria exist, it remains a diagnosis of exclusion, especially with ancillary techniques aiding the recognition of established as well as more recently described neoplasms. Other medullary-based malignancies included in the differential diagnosis include renal medullary carcinoma/renal cell carcinoma unclassified with medullary phenotype, fumarate hydratase-deficient renal cell carcinoma, and upper tract urothelial carcinoma. Moreover, other rare entities should be excluded, including metastatic carcinoma, lymphoma, and melanoma. In addition to potential prognostic differences, accurate diagnoses can have important surgical and clinical management implications.

Progress of Tumor Growth and Metastasis After Inoculation of B16FO Melanoma Cells in Kidney of Female Nude Mice Is Inhibited by a Novel Nutrient Mixture

Background: Tumor metastasis is a major cause for most cancer-related deaths. Melanoma is a serious cancer that metastasizes to other areas of the body, including the lungs, liver, brain, bones, or lymph nodes. Currently used cancer therapies are ineffective with a high degree of toxicity and patient mortality. Thus, any successful treatment for melanoma must target metastasis. Methods: We studied the effect of a novel nutrient mixture (NM) containing ascorbic acid, lysine, proline, green tea extract, quercetin, and others, on the inhibition of melanoma growth and metastasis after inoculation of B16FO melanoma cells into the left kidney of female nude mice. Female athymic mice (n = 10) 8 to 10 weeks of age, were inoculated superficially in the left kidney with 5 × 10⁵ B16FO melanoma cells in 100 µL of media. The right kidney was left untreated. After inoculation, the mice were randomly divided into 2 groups. The control group (n = 5) was fed a regular rodent chow diet, and the test group was given the same diet supplemented with 0.5% NM. The animals in control and the test groups were sacrificed 2 weeks later. Each animal’s abdominal cavity was opened, and the kidneys, lungs, liver, and spleen were excised and examined for tumor growth and metastasis. Results: The kidneys in the control group weighed 25% to 30% more than those in the NM group due to colonization of B16FO melanoma cells. No metastasis to the liver or spleen was observed in either of the groups. However, severe lung metastasis was observed in the control group and mild to moderate metastasis was observed in the NM group. Conclusion: These results show that the NM is effective in mitigating the growth of tumors in the kidney and metastases to the lung.