Pterygium inversum unguis

INTRODUCTION

Pterygium inversum unguis is a rare nail abnormality where there is adherence of the distal nail bed to the ventral surface of the nail plate obliterating the distal nail groove. This condition may be congenital or acquired. The acquired conditions are usually associated with various connective tissue disorders like systemic lupus erythematous, progressive systemic sclerosis etc.

CASE REPORT

A 11-year old girl born of second degree consanguineous marriage presented to our OPD with nail abnormality of the 2^nd toe of both feet present since birth. It was asymptomatic until 8-months ago when she developed pain in those toes while walking. Her younger sister aged 8-years, also gave history of similar abnormality of 2^nd toe of both feet present since birth. She was asymptomatic.

On examination distal nail bed was adherent to the ventral surface of the nail plate. It was soft to palpate and was tender in the elder sister. There were no other complaints or abnormalities in both the sisters. There was no similar complaint in any of the family members. Subungual exostosis was ruled out in both sisters by taking radiographic images of both feet. Hence diagnosis of pterygium inversum unguis probably of autosomal recessive inheritance was made.

DISCUSSION

Pterygium Inversum Unguis (PIU) is a rare nail abnormality which was first described by Caputo and Prandi in 1973. It is characterized by adherence of hyponychium to the underside of nail plate.¹

Acquired conditions are associated with various connective tissue disorders like scleroderma,² systemic lupus erythematous, rheumatoid arthritis etc.,

This condition was also reported to be associated with leprosy.³

Two patients with stroke have been found to have acquired pterygium inversum unguis. In one case there was bilateral involvement of fingers,⁴ in the other there was unilateral involvement.⁵

PIU can also occur as allergic reactions to acrylics especially formaldehyde containing nail hardeners.⁶

Most of the cases with PIU have been found in women between the ages 20 and 70 years. Finger nails are affected more common than toes. They usually have a bilateral occurrence with involvement of all toes or finger nails or few nails of both.⁴

Congenital PIU occurring on the 4^th toe as autosomal recessive trait has been described.⁷

Here in we report PIU occurring in two sisters born of 2^nd degree consanguineous marriage involving the 2^nd toe bilaterally with no similar history in the family. Use of force to push back the advancing hyponychium is an extremely painful approach resulting in severe bleeding.

Hence the treatment of this condition poses a great challenge.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

REFERENCES

1. 1. Caputo R, Prandi G. Pterygium inversum unguis. Arch Dermatol. 1973;108:817-8.
2. 2. Patterson W. Pterygium inversum unguis-like changes in scleroderma. Report of four cases. Arch Dermatol. 1977;113:1429-30.
3. 3. Patki AH. Pterygium inversum unguis in a patient with leprosy. Arch Dermatol. 1990;126:1110b.
4. 4. Vadmal Manjunath, Reyter Ilya, Oshtory Shaheen, Hensley Benjamin, Woodley David T. Pterygium inversum unguis associated with stroke. J Am Acad Dermatol. 2005;53:501-3.
5. 5. Morimoto SS, Gurevitch AW. Unilateral Pterygium inversum unguis. Int J Dermatol. 1988;27:491-4.
6. 6. Norton LA. Common and uncommon reactions to formaldehyde-containing nail hardeners. Semin Dermatol. 1991;10:29-33.
7. 7. Yotsumoto S, Kanzaki T. Curved nail of the fourth toe. J Am Acad Dermatol. 1999;40:123.