RESUMEN: Se presenta el caso de una Joven de 14 años con adenomegalias cervicales bilaterales masivas, con diagnóstico clínico de linfoma y cuyo estudio anatomopatológico demostró los hallazgos morfológicos de la histiocitosis sinusal con linfadenopatía masiva. Esta entidad debe tenerse en cuenta en todo diagnóstico diferencial de adenomegalias masivas en niños o pacientes Jóvenes, pues el curso clínico y el pronóstico en general son benignos.ABSTRACT: The case of a 14 year-old girl with massive, bilateral, cervical adenopathies is reported. The Initial diagnosis was a Iymphoma but histological study revealed typical changes of sinusal histiocytosis with massive Iymphadenopathy. The patient was treated with acyclovir and two months later left adenopathies had considerably decreased while the right ones remained unchanged. This disease should be taken Into account In the differential diagnosis of massive adenopathies in children or young people. Its clinical course and prognosis are usually benign.