Diagnosis and clinical behavior in patients with Lynch-like syndrome. / Diagnóstico y comportamiento clínico de pacientes con sospecha de síndrome de Lynch sin mutación conocida.

INTRODUCTION AND AIMS: Lynch-like syndrome is diagnosed when there is an expression deficit in DNA mismatch repair proteins but a normal genetic study. The behavior and management of that pathology are currently a subject of debate. We present herein the characteristics of patients with Lynch-like syndrome, together with a surveillance proposal. MATERIALS AND METHODS: Immunohistochemistry was carried out on families suspected of presenting with Lynch syndrome. Germline analysis was done if there was loss of mismatch repair protein expression and no BRAF mutation. RESULTS: Of the 148 patients that underwent immunohistochemistry testing, 23 presented with loss of mismatch repair protein expression. Seven of those patients were identified as having Lynch-like syndrome: 3had colon cancer, 2had endometrial tumor, and 2were healthy, with an affected relative. Mean patient age was 56.9 years and only one patient presented with another tumor associated with Lynch syndrome. CONCLUSIONS: Until there is a better understanding of the etiology of that heterogeneous entity, intermediate surveillance is an adequate strategy.