presenting as isolated extranodal involvement of larynx (medical condition): A form of sinus histiocytosis characterized by lymphadenopathy as well as involvement of other tissues such as the sinus cavity, skin, lungs, bone, eyes, kidneys, testes, head and neck area and the central nervous system. Symptoms vary according to the organ involved. The condition usually runs a prolonged course with spontaneous remission occurring in some cases. Rare cases may be fatal. See also Asrar-Facharzt-Haque syndrome