INTRODUCTION

Pachyonychia congenita (PC) describes a group of rare autosomal dominant skin disorders characterized predominantly by dystrophic, thickened nails and painful and highly debilitating palmoplantar hyperkeratosis [1,2]. With a base on phenotypes, PC is classified in four types: PC I to III and PC tarda [3,4]. The objective of this case report is to describe the clinical features of PC-I.

CASE REPORT

A 10 year-old male born at preterm to non consanguineous parents was referred to our outpatient clinic for evaluation of thickened nails starting at the age of 6 months.

The boy had been born prematurely at 34 weeks’ gestation after premature contractions and prolonged rupture of membranes. No maternal fever, tachycardia, chorioamnionitis, or other complications had occurred. The boy had stayed in neonatal intensive care for 4 weeks because of feeding issues, and he had been transiently on nasal continuous positive airway pressure therapy, from which he was weaned to room air after 3 days of life. He was discharged at 38 weeks’ gestation. He presented with history of pinhead-sized yellowish spiny skin lesions all over body noted at birth that had slowly grown during the first year of age and abnormalities nails. No history of natal or neonatal teeth. The patient intelligence was normal. No similar complaints in family.

Physical examination showed:

1. All 20 nails were thickened, yellowish discolouration with increased curvature and subungual hyperkeratosis (Fig 1).

Figure 1: 20 thickened nails, yellowish discolouration with increased curvature and subungual hyperkeratosis.

2. All toe nails were thickened, dystrophy, yellowish discolouration and subungual hyperkeratosis (Fig. 2).

Figure 2: 20 thickened nails, yellowish discolouration with increased curvature and subungual hyperkeratosis.

3. Skin: Multiple follicular discrete papules present over the face, neck and upper chest (Fig. 3).

Figure 3: Multiple follicular discrete papules present over the face, upper chest, buttock, elbow, knees and flexures.

4. Multiple hyperkeratotic papules present over the back of neck, back of chest, buttock and elbow (Fig. 4).

Figure 4: Multiple follicular discrete papules present over the face, upper chest, buttock, elbow, knees and flexures.

5. Focal plantar keratoderma (Fig. 5).

Figure 5: Focal plantar keratoderma.

There were no abnormalities in examination of otolarynx and ophthalmology.

All laboratory investigations were within normal limits. KOH mounts of toe and finger nails were negative for fungal elements. Histopathology examination of Follicular keratotic papule showed follicular plugging, hyperkeratosis and acanthosis. Skin biopsy of Sole showed marked hyperkeratosis, acanthosis, moderate hyper granulosa’s and minimal dermal inflammatory infiltration. Based on characteristic clinical findings and histopathology features, diagnosis of pachyonychia congenital type1 or Jadassohn – Lewandowsky syndrome.

Pachyonychia congenita (PC) is a rare, autosomal dominant disorder characterized by triad of subungual hyperkeratosis with accumulation of hard keratinous material beneath the distal portion of the nails, lifting the nails from the nail bed, keratosis palmaris et plantaris with thick callosities, especially on the soles and thick white areas on the oral mucosa [5]. Other associated features which may occur include keratosis pilaris, hyperkeratotic follicular papules on the sites of friction, hair abnormalities and hyperhidrosis of the palms and soles. These disorders have been suggested to be due to mutations in paired keratins, K6a/K16 (in PC1) and K6b/K17 (in PC2). According to these mutations, various clinical variants have been described:

PC-I or Jadassohn – Lewandowsky syndrome (MIM #167200) is a common entity characterized by onychogryposis on all the digits (100%), hyperkeratosis of the palmo plantar (50-90%) and of extensor areas, follicular keratosis (37%), oral (50-75%) or laryngeal (6-15%) leukokeratosis, acral hyperhidrosis (20-75%) and blisters (36%) [2–7,8,9].

In patients with PC-II or Jackson- Lawler syndrome (MIM #167210) main changes are natal or neonatal teeth (15-50%), cutaneous cystic lesions (25%), disorders in scalp and eyebrow hairs (9-25%), in addition to corneal dystrophy (8%); moreover, the nail hyperkeratosis is less accentuated in PC-II than in PC-I [3,6,7,8,9].

PC-III (Schafer-Brunauer syndrome) shows ccombined features of type 1 and 2 with angular cheilosis, cataract and corneal dyskeratosis. [4]. Despite recent advances in genetic analysis, Misdiagnosis can occur because same mutations may show diverse features [10].

A fourth variant, PC tarda, has also been described and is characterized by a later onset that ranges from late childhood to middle ages.

Other rare variants include pachyonychia congenital with only nail involvement. Patients with PC often present at birth or soon after with the characteristic hypertrophic toenail dystrophy [11].

CONCLUSION

PC is a rare genetic disorder for which there are very few therapeutic options are available. Free genetic testing is provided to each patient through the International Pachyonychia Congenita Research Registry(IPCRR) sponsored by the PC Project (www.pachyonychia.org) which is a non-profit USA public charity, supports clinical and research activities related to the treatment of pachyonychia congenital. By building a patient community through the IPCRR and a physician and researcher community through the IPCC, PC Project is moving research forward to better understand the condition and to develop effective treatments.

In India we don’t have such projects working on PC. With this case, we intend to draw attention to this condition and the role of the dermatologist in the diagnosis. To our best of the knowledge this represents the first report of isolated PC in siblings with healthy parents.