From the Journals

Leptin expression may help differentiate renal lesions



Expression of leptin could help differentiate benign renal oncocytomas from chromophobe renal cell carcinoma (RCC), results of a recent pathology study suggest.

Renal oncocytomas had significantly increased nuclear expression of leptin, compared with the eosinophilic subtype of chromophobe RCC, according to the study.

If translated into clinical urology and pathology practice, quantification of leptin expression could help in the difficult task of differentiating between these renal lesions, according to the investigators, led by Glenda Gobe, PhD, of the Kidney Disease Research Group at the University of Queensland in Brisbane, Australia.

“This may have a major clinical impact in reducing unnecessary intervention and treatment-related harm,” Dr. Gobe and her colleagues reported in Pathology.

They obtained archived paraffin blocks from human renal tumor tissue obtained between 2009 and 2014. Paraffin sections were immunostained for leptin and leptin receptors.

The investigators evaluated 30 chromophobe RCC specimens – 15 eosinophilic and 15 noneosinophilic variants – and 15 renal oncocytomas. They also included 30 clear cell RCCs, the most common histological subtype of RCC, to verify immunohistochemistry (IHC) staining patterns.

Results showed that both leptin and leptin receptor IHC was significantly increased in tumor versus in matched, noncancerous kidney tissue.

Expression of both leptin and leptin receptor was highest for renal oncocytomas versus both the chromophobe and clear cell RCCs. On closer scrutiny, the investigators said, nuclear expression of leptin in renal oncocytomas had a significantly higher intensity versus chromophobe RCC.

“This important finding could prove to be helpful in the distinction between chromophobe RCC and renal oncocytoma,” Dr. Gobe and her coauthors wrote in their report.

In a subgroup analysis, they found a significantly increased nuclear leptin intensity for the renal oncocytomas as compared to the eosinophilic variants of chromophobe RCC (P = .016 by Dunn’s multiple comparisons test).

By contrast, testing did not reveal a significant difference for renal oncocytomas versus noneosinophilic chromophobe RCC (P = .0939) or versus clear cell RCC (P greater than .999).

Leptin, secreted by adipose cells that help regulate energy balance through inhibition of hunger, may play a role in carcinogenesis, according to investigators. Studies to date have shown that the hormone may impact carcinogenesis through cell proliferation, inhibition of apoptosis, and other potential mechanisms.

Applying this biomarker in clinical practice could more reliably characterize renal lesions with no or limited malignant potential, according to the investigators.

“The distinction of renal oncocytoma from chromophobe RCC will dictate different management pathways, as renal oncocytoma is benign while chromophobe RCC is a malignant subtype which will require further surveillance,” Dr. Gobe and her coinvestigators wrote.

The University of Malaya, Kuala Lumpur, Malaysia, funded the study. Dr. Gobe and her coauthors stated that they had no conflicts of interest.

SOURCE: Gobe G et al. Pathology. 2018 Aug;50(5):504-10.

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