Multiphoton microscopy for rapid histopathological evaluation of kidney tumours.

OBJECTIVE: To explore the potential of multiphoton microscopy (MPM) for rapid evaluation and triaging of ex vivo kidney tissue.

MATERIALS AND METHODS: Fresh neoplastic and non-neoplastic tissues from nephrectomy specimens (n = 40) were imaged with MPM and later submitted for routine histopathology.

RESULTS: On MPM, normal kidney architecture was evident and clearly distinguishable from tumour. Forty malignant tumours (20 clear-cell renal cell carcinomas [RCCs], 10 papillary RCCs, five chromophobe RCCs and five papillary urothelial carcinomas [UCs], as diagnosed by haematoxylin and eosin staining) were imaged and subtyped as non-papillary and papillary, based on their architecture. Non-papillary tumours were further classified based on their unique cytoplasmic signatures. Clear-cell RCCs had a predominant population of cells with fat droplets in cytoplasm. Chromophobe RCCs had cells with non-fatty/homogeneous cytoplasm and distinct intra-cytoplasmic granules. Papillary RCCs had single-cell-lined papillae with often abundant histiocytes in their core, whereas PUC had multi-layered urothelium-lined papillae. The diagnostic accuracy of tumour subtyping by two independent uropathologists was 95%.

CONCLUSIONS: We showed that MPM can reliably differentiate neoplastic from non-neoplastic kidney tissue and subtype kidney tumours in fresh, unprocessed tissue, MPM might therefore be useful as a rapid real-time diagnostic tool for the evaluation of kidney biopsies, and surgical margins in partial nephrectomies, to improve overall patient management.