A portable medical diagnostic instrument includes an instrument head and a handle portion having an open-ended receiving cavity. A compact illuminator defined by a housing retaining a miniature light source and a power supply is releasably fitted within the open-ended receiving cavity of the handle portion wherein the light source of the illuminator is optically coupled with the instrument on assembly therewith. The handle portion can be integral with the instrument or releasably attached. The handle portion according to at least one version is made from a plastic or other suitable material, permitting disposability and/or single patient use. In one version, the handle portion is flexibly deformable, at least partially, to facilitate release of the portable illuminator.