Subungual exostosis on index finger in a child

Piyush Kumar, Ghuncha Alam

 Department of Dermatology, Katihar Medical College, Katihar, Bihar, India

Correspondence Address:
Piyush Kumar
Department of Dermatology, Katihar Medical College, Katihar, Bihar
India

A 7-year-old boy presented with a slow growing painful swelling under the nail of right index finger for 3 years. There was no history of prior trauma or chronic infection. The subungual nodule of around 1 cm in size was well-defined, bony hard, slightly tender, with a hyperkeratotic surface. Overlying nail plate was separated from nail bed and showed features of dystrophy [Figure - 1]a and [Figure - 1]b. Radiographs of the hand revealed an outgrowth of trabeculated bone projecting from and in continuity with distal phalanx of the right index finger on the dorsal aspect, with intact well-defined cortical margins. No destructive changes were noted in the distal phalanx [Figure - 1]c. These radiological findings confirmed the diagnosis of subungual exostosis. The patient was referred to the department of orthopedics for further management.

Figure 1a: Dorsal view of bony hard nodule on dorsal aspect of terminal phalanx. Overlying nail plate is dystrophic and separated from nail bed

Figure 1b: Lateral view of nodular growth on dorsal aspect of terminal phalanx

Figure 1c: Radiograph showing radio-opaque mass overlying and in continuity with terminal phalanx of index finger

Subungual exostosis is more common on toes and develops mostly during adolescence. Subungual exostosis is considered rare in young children and on fingers. Differentials include subungual verruca, carcinoma of the nail bed, keratoacanthoma, subungual epidermoid inclusions and Koenen tumor. All these entities are radiolucent. Enchondroma presents in a similar manner clinically, but it is radiolucent and causes expansion of phalanx itself. Subungual exostosis is treated surgically by excision and it needs to be excised up to the normal bone tissue, to prevent recurrence.

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Conflicts of interest

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