A novel case of t(X;1)(p11.2;p34) in a renal cell carcinoma with TFE3 rearrangement and favorable outcome in a 57-year-old patient

Renal cell carcinoma (RCC) with translocation involving Xp11.2 (Xp11.2-RCC) is a rare neoplasm that usually occurs in children and young adults. This incidence is underestimated in adults because its morphological similarities with clear-cell RCC or papillary RCC2,3, as well as immunohistochemical and cytogenetic analyses are not carried out systematically in adults. We present a novel case of Xp11.2-RCC in a 57-year-old woman. The histologic features were those of a clear-cell RCC. Molecular cytogenetic analysis showed an uncommon t(X;1)(p11.2;p34) with TFE3 rearrangement and no alteration of chromosome 3. The immunohistochemical analysis showed expression of the TFE3 protein. Only nine cases of (X;1)(p11.2;p34) have been published, most of them occurring in children or young adults. To our knowledge, this is the second report of such a translocation in a patient older than 55 years. After a follow-up period of 13 months, the patient showed no evidence of disease. The clinical outcome was favorable, indicating that this particular translocation might be associated with a good prognosis. This observation confirms that Xp11.2-RCC are very likely to be underestimated in adults older than 40 years, and it highlights the importance of performing immunohistochemical and cytogenetic analyses in RCC for accurate diagnosis.