Isolated progressive macrodactyly belongs to a heterogeneous group of congenital overgrowth syndromes, resulting in enlargement of all tissues localized to the terminal portions (fingers or toes) of a limb. The aim of this case report is to create further awareness among physicians on this rare clinical entity and present a short review of the literature. We present the case of a 10-year-old Nigerian girl with a history of progressive overgrowth of left thumb since birth. The patient‟s facies and body habitus were normal without hemihypertrophy. Anthropometric measurements of the child‟s hands, revealed an overgrowth of the left thumb compared with the right. The child had no café-au-lait spots or any other skin lesions. The radiograph of the hands revealed increase in size of both soft tissue and phalangeal bones (enlongated and broadened) of the left thumb. A diagnosis of isolated progressive left thumb macrodactyly was made and the patient was referred to the orthopaedic surgeon for surgical intervention. The child and her parents suffered psychological distress. Isolated progressive macrodactyly is very rare but it is cosmetically displeasing to the child, resulting in psychological distress.