A Sporadic Case of Ichthyosis Hystrix: Curth and Macklin Type.

Sir,

A 13-year-old female presented with generalized skin lesions since early childhood. She was born healthy out of non-consanguineous marriage and full-term vaginal delivery, according to history given by her mother. After 1 year, she started developing lesions initially over the joints such as elbow and knee, which then gradually progressed to involve other parts of the body. None of the other family members were affected.

There was no history of blistering and hearing loss. On examination, diffuse, hyperkeratotic, thick, dry, adherent, mudcolored to hyperpigmented scales were seen covering most of the body. Face, neck, and upper part of the trunk was spared, but nipple and abdomen were involved [Figure 1]. Joints, especially the knee and elbow, had porcupine like spikes with verrucous ridged to cobblestoned plaques [Figure 2a]. Hyperkeratotic plaques were present over dorsum of hands [Figure 2b] and feet. Palms and soles had severe keratoderma and fissures [Figure 3a and b]. Scalp, hair, orogenital area, teeth, and nails were normal. Liver function showed raised serum alkaline phosphatase levels. Vitamin D levels were low. Other investigations were normal. Biopsy taken from one of the plaque over the back showed marked hyperkeratosis and papillomatosis in the form of crest-like projections of epidermis [Figure 4a], that was accompanied by perinuclear vacuolization and binucleated keratinocytes [Figure 4b]. The dermoepidermal junction showed mild lymphoplasmacytic infiltrate with occasional melanophages in otherwise unremarkable dermis. On the basis of the clinical features and histopathology, we arrived at the diagnosis of ichthyosis hystrix of Curth and Macklin type.

Figure 1

Thick hyperkeratotic plaques involving the nipple and abdomen

Figure 2

Verrucous ridged to cobblestoned plaques over (a) knees; (b) hyperkeratotic plaques involving dorsum of hands

Figure 3

Severe keratoderma and fissures over (a) palms and (b) soles

Figure 4

(a) Hyperkeratosis and papillomatosis in the form of crest-like projections in epidermis (H and E, ×10); (b) epidermis showed perinuclear vacuolization and binucleated keratinocytes (H and E, ×40)

Ichthyosis hystrix is a rare genodermatosis. It is a type of congenital ichthyosis, and is also known as systematized verrucous epidermal nevus. It presents with massive hyperpigmented and hyperkeratotic verrucous plaques mainly over the extensor aspect of the arms and legs. Inheritance is either autosomal dominant or sporadic.[1]

The word hystrix means porcupine-like. It was first documented between 1731 and 1851 in the Lambert family of Suffolk.[2] Ichthyosis hystrix includes Brocq, Lambert, Curth and Macklin, Rheydt, and Bäfverstedt types.[2]

Ichthyosis hystrix of Curth and Macklin type is a rare autosomal dominant disorder with very few sporadic cases[3] reported since its first description in 1954. It is characterized by extensive, spiky, or verrucous, hyperkeratotic, ridged, or cobblestoned plaques over the large joints, hyperkeratotic papules on the trunk and extremities, with massive palmoplantar keratoderma leading to deep, bleeding, and painful fissures. Electron microscopy shows perinuclear shells in binucleated suprabasal keratinocytes.[4] Curth and Macklin type is caused by heterogeneous frame shift mutation in keratin 1 gene (KRT 1), a new mutation for this disease has recently been reported.[5]

It is considered to be a type of epidermal nevus with bilateral distribution, which involves extensive part of body surface including extensors, flexures, as well as other sites of the body such as scalp with mild scaling. Patients may present at birth or there may be a delayed onset in infancy or childhood, as seen in our patient.

The distinctive distribution of lesions, associated abnormalities, and inheritance patterns help to differentiate between different forms of ichthyosis hystrix. In Brocq type, erythroderma and blistering is characteristic, and nevoid forms are less common, whereas Rheydt type shows hyperkeratosis over the face and limbs along with hearing loss. Bäfverstedt type is very rare type of ichthyosis hystrix in which ichthyosis occurs especially over the face with striking follicular hyperkeratosis and mildly affected palms.[6] Lambert type is characterized by spiny scales covering the entire body except the face, palms, soles, and genitals, with no history of blistering. Patients are normal at birth but develop lesions at the age of 7 weeks or later.

Histopathology shows features of epidermal nevi with prominent epidermolytic hyperkeratosis which refers to the combination of compact hyperkeratosis, binucleate keratinocytes with perinuclear vacuolization in upper layers of epidermis, and coarse keratohyalin granules. Acanthosis and papillomatosis are also seen. This can be further confirmed by electron microscopy which also reveals keratin intermediate filaments aggregated into continuous, peripheral shells, without keratin clumping, which is typical for epidermolytic hyperkeratosis.

Recently, it has been suggested to rename the entity as Ichthyosis Curth–Macklin and group it under keratinopathic ichthyoses, along with epidermolytic ichthyosis and superficial epidermolytic ichthyosis. As per our literature search, only three cases of Ichthyosis hystrix of Curth–Macklin type have been reported from India till date.[789] In our case, family history was negative suggesting sporadic presentation of Curth–Macklin type which is a very rare entity.

Epidermolytic hyperkeratosis was the closest differential diagnosis, but it was ruled out by absence of blistering at birth and presence of spiny palmoplantar hyperkeratotic scales. Treatment of generalized cases is difficult. Localized cases can be managed with keratolytics and emollients to decrease the keratoderma and scaling. Systemic retinoids also show some benefits.

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Conflicts of interest

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