Pachyonychia congenita is a rare hereditary disorder characterized by gross thickening of all finger and toenails. We report an infant who had clinical features consistent with pachyonychia congenita type II, with unusual features of microcephaly, seizures, electroencephalogram abnormalities, failure to thrive, and heterochromia iridis.

Key words: Congenital dyskeratosis, Nail dystrophy, Pachyonychia congenital.

Pachyonychia congenita has both autosomal dominant and autosomal recessive forms of inheritance, reflecting heterogeneity(2). PC encompasses a range of inherited ectodermal dysplasias, divided into two main subtypes, Pachyonychia congenita type 1 (PC-1, Jadassohn-Lewandowski syndrome) and Pachyonychia congenita type 2 (PC-2, Jackson-Lawler syndrome), which can usually be distinguished by clinical examination. Considerable overlap can occasionally exist between PC-1 and PC-2, which can make diagnosis difficult. This most recent classification of PC is based on clinical findings and by molecular genetic testing(3).

The predominant and most common clinical feature in PC is hypertrophic nail dystrophy. Other findings common to PC-1 and PC-2 are: focal palmoplantar keratoderma, blistering, oral leuko-keratosis, and palmoplantar hyperhidrosis, follicular keratosis on trunk and extremities, and piloseba-ceous cysts. Other findings observed in PC-2 are steatocystoma which normally develops at puberty, pili torti (hair anomalies) and natal teeth(3). The pattern of Pachyonychia congenita correlates well with the keratin gene mutation. The two keratin genes known to be associated with PC-1 are KRT6A and KRT16 and the two keratin genes known to be associated with PC-2 are KRT6B and KRT17(3). PC should be differentiated from traumatic thickening of nails and from congenital onychogryphosis, which are easy to recognize because they do not involve all nails and are not associated with dyskeratotic skin lesions. Based on the clinical manifestation, our cae appear to be type II, as per recent classification(3). Hoarseness is a feature of PC-1 but may also be seen in PC-2 along with unruly hair. The relationship of mental retardation to Pachyonychia congenita is not clear. It has been suggested that the fetal ectodermal lesions that affect the skin may also affect the central nervous system(4). Our case in addition had other unusual features namely microcephaly, seizures(1), electro-encephalogram abnormalities(5) and failure to thrive(4), which have been described in few previous isolated case reports. However, a combination of all these unusual features has not been described earlier. The presence of heterochromia iridis may be another new association of pachyonychia congenita or may just be a chance occurrence.

Treatment of PC primarily provides symptomatic relief. Emollients, keratolytics, topical retinoids and oral retinoic acid are used to treat palmoplantar hyperkeratosis(6). The only effective treatment for nail lesions is surgery with radical excision of the nail, nail bed, and nail matrix, and skin implantation at the site of the removed nail(7).

Contributors: SBS, KK were involved in case management. KK, BR were involved in review of literature and preparation of manuscript. SBS will act as guarantor.

Funding: None.

Competing interests: None stated.

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3. Smith FJ, Kaspar RL, Schwartz ME, McLean WH, Leachman SA. Pachyonychia Congenita. Gene Reviews. http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=pc. Accesed 31 August, 2008.

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6. Rohold AE, Brandrup F. Pachyonychia congenita: therapeutic and immunologic aspects. Pediatr Dermatol 1990; 7: 307-309.