[Immunohistochemical characterisation of the main histologic subtypes of epithelial renal tumours on tissue-microarrays. Study of 310 cases]

Abstract

Objective: Diagnosis of renal epithelial tumours of adult is often easily made. Nevertheless, it can be difficult to distinguish clear cell carcinoma (CCC) and chromophobe carcinoma (CCHRO), or the eosinophilic variants of CCC and CCHRO with papillary carcinoma (CTP) and oncocytoma (ONCO). The objective is to study and validate immunohistochemical phenotypes of these tumours and to evaluate if they are helpful and to define a diagnostic strategy.

Materials and methods: 310 tumours (75 CCC, 89 CTP, 50 CCHRO and 96 ONCO) were collected and put on 4 tissue-arrays blocks. Immunohistochemical stainings were performed with some usual antibodies: pancytokeratin AE1-AE3, EMA, vimentin, CD10, CK7, CK20 and RCC (Renal Cell Carcinoma).

Results: Pancytokeratin AE1-AE3 is expressed mainly in CTP (82.5%). The cytoplasmic staining of EMA is seen in almost all CCHRO (98%) and more than half of CTP (57%). Vimentin is rather specific of CCC (54.5%) and CTP (85%) whereas it is negative in ONCO and CCHRO. CD10 is expressed in the majority of CCC (86.5%) and in some of CTP and CCHRO 65 and 39% respectively. CK7 is rather specific of CTP and CCHRO with 79 and 81.5% of positivity rate. Based on statistical analysis, we have built a diagnostical tree allowing to distinguish 79% of tumours using only three antibodies: CK7, vimentin and CD10.

Conclusion: CCC are CK7-/Vim-/CD10+ or CK7-/Vim+; CTP are CK7+/Vim+; CCHRO are CK7+/Vim-; and ONCO CK7-/Vim-/CD10-. In the oncocytoma/chromophobe group, ONCO are more often CK7-/EMA- and CCHRO CK7+/EMA+.