Pachyonychia congenita. Electron microscopic and epidermal glycoprotein assessment before and during isotretinoin treatment

Pachyonychia congenita: A rare genodermatosis

Pachyonychia congenita (PC) is a rare genodermatosis with only 450 cases reported since 1906. It is of two types, type I due to mutation in genes 6a and 16, and 6b and 17 in type II with an autosomal dominant inheritance in both types. A 22 yr old female patient presented in our OPD with hypertrophy of finger and toe nails, palmoplantar keratoderma, oral punctuate leukokeratosis, hyperhidrosis in palms and soles with maceration and malodour since childhood. She had a positive family history with father and grandfather affected but less severely. Microscopy and culture of nail clippings and scrapping were done to rule out fungal infection. On biopsy acanthotic epidermis, parakeratosis, orthokeratosis were seen. No evidence of any associated malignancy was found after thorough workup. She was diagnosed as PC Type 1. She was put on topical steroids and orally on acetretin 25 mg OD. Paring of the nails was done too reduce the thickness of nails & to provide symptomatic relief. She was on a regular treatment for 3-4 months and showed some improvement in the form of reduced palmoplantar hyperkeratosis and reduced oral punctate keratosis but was later lost on followup. She showed no adverse effect to therapy during this period. This case is being reported because of its rarity.

Pachyonychia congenita tarda

Pachyonychia congenita is a distinct hereditary disorder of keratinization, in which dystrophy of all nails is associated with palmoplantar keratoderma and other hyperkeratoses. Recently a late-onset type has been reported. We report a second family with late-onset pachyonychia congenita, showing a remarkable clinical heterogeneity. Furthermore, one patient demonstrated a number of associated hyperkeratoses not previously recognized. Acitretin proved useful in the treatment of this late-onset form of pachyonychia congenita.

A gene for pachyonychia congenita is closely linked to the keratin gene cluster on 17q12-q21

Pachyonychia congenita (PC) is a group of hereditary syndromes which have in common a hypertrophic dystrophy of the distal nail, and are associated with a variety of additional features, notably various dyskeratoses of skin and mucous membranes. The pathology is unknown but the array of clinical features suggests the possibility of a keratin abnormality. In the present report we describe linkage analyses in a large PC pedigree of the Jackson-Lawler type, a subtype which is characterised by multiple epidermal cysts, hair abnormalities, and natal teeth. The disease locus in this family was found to be tightly linked to markers mapping within, or very close to, the keratin type I cluster at 17q12-q21; maximum lod scores for linkage of the disease to a KRT10 polymorphism and to D17S800, a marker known to be very tightly linked to KRT10, were respectively +4.51 and +7.73, both at theta = 0.00. Although always likely, our findings provide strong evidence of a keratin gene anomaly underlying an inherited disorder affecting epidermis, nail, hair, and mucosa. These findings permit testing to see if pachyonychia congenita shows any locus heterogeneity and suggest specific candidate keratin genes for mutation searching studies. In addition, they suggest a role for keratins in the phenomenon of natal dentition.

Pachyonychia congenita: a clinical study of 12 cases and review of the literature

Twelve cases of pachyonychia congenita were reviewed. The mode of inheritance was autosomal dominant. The clinical features of these patients included thickened nails, hyperkeratosis of the palms and soles, thinning of hair or alopecia, painful bullae or ulcerations of the palms and soles, leukokeratosis oris, verrucous lesions of the extremities, hyperhidrosis, premature eruption of teeth, paronychial infections, epidermal cysts with milia, and corneal dyskeratosis at times associated with cataracts. Biopsy from the plantar lesions usually revealed marked hyperkeratosis, acanthosis, moderate hypergranulosis, and minimal dermal inflammatory infiltration. Treatment with keratolytic agents and lubricants is indicated to areas of palmar and plantar hyperkeratosis but usually produces only transient benefit. Squamous cell carcinoma developed in one of the patients over the site of chronic plantar ulcerations. Areas of chronic bullous formation or ulceration should be observed for possible skin malignancy.