A 2 years 6 months old otherwise healthy female child was referred from the department of pediatrics for cracked feet and palms. She was accompanied by her mother and maternal grandmother who were our informant(s) as well. On cutaneous examination we found that there was diffuse thickening of palms and soles which was accompanied with deep fissuring. The fissures made walking difficult. The mother stated that, the girl had no abnormal dermatological manifestation at birth, the lesion started to evolve after infancy after one year of birth. After questioning and examining the mother we found out that she also had similar lesion since she was 2 years old and this was confirmed by her mother who also accompanied them to our Out-patient Department (OPD) and who was free of the disease. The lesion in both the mother and daughter was confined to both palms and soles with well demarcation at wrist and feet, sparing the dorsal surfaces of hand and feet (Figure 1). 

Figure 1: The Lesion in both the Mother and Daughter was Confined to Both Palms and Soles with Well Demarcation at Wrist and Feet, Sparing the Dorsal Surfaces of Hand and Feet

Oral mucosa, teeth and nails were not involved in both the mother and daughter. Histopathological examination of the biopsy taken from the sole of the patient revealed massive orthokeratotic hyperkeratosis, hypergranulosis and acanthosis without epidermolysis which was consistent with Unna-Thost disease (Figure 2).

Figure 2: Histopathological Examination of the Biopsy Taken from the Sole of the Patient Revealed Massive Orthokeratotic Hyperkeratosis, Hypergranulosis and Acanthosis without Epidermolysis which was Consistent with Unna-Thost Disease

After relevant blood investigations which was found to be within normal limits, we discharged the patient with topical emollient and a keratolytic agent (urea 40%). Following 2 weeks of regular treatment the patient came for review in our OPD and thereby we found that there was around 50% reduction in hyperkeratosis with healing of cracks and fissures.

Palmoplantar Keratodermas (PPK) form a category of disorders typified by disproportionate epidermal thickening of the palms and soles. PPK may be inherited or acquired [1]. On the basis of the underlying genetic defect and its phenotypic manifestation(s), inherited PPKs may be divided into: 

• Non-syndromic, isolated PPKs-which are characterized by a unique or predominant palmoplantar involvement

• Complex PPKs-non-syndromic PPKs with additional distinctive cutaneous and adnexal manifestations, here named

• Syndromic PPKs - in this type PPK is associated with specific extracutaneous manifestations [2,3]

The mutations in the genes which encodes for different proteins involved in keratinization process, like desmosomes, keratins, loricrin, gap junction proteins, cathepsin C and many others have been involved in the pathogenesis of PPK. Majority of patients of PPK manifests in infancy in isolation and in rest it is found in association with other abnormalities of nails, teeth, or other organs [4].

Vorner's keratoderma (epidermolytic keratoderma) and Unna-Thost keratoderma (non-epidermolytic) are two major types of non-transgradient diffuse palmo-planter keratoderma inherited as autosomal dominant trait. The disease present with hyperkeratosis of palms and soles in infancy which becomes evident by early childhood and persists throughout life. Unna first described a family with this peculiar syndrome in 1880. K1 and K9 mutation observed in Vorner's keratoderma and K1 and K2 mutation in Unna-Thost keratoderma. In both cases the onset is in the first few months of life and the pathological lesions are fully developed by the 3-4 years of age. 

They usually present with even, thick, yellowish hyperkeratosis over palms and soles delineated by a sharp border at the dorsoventral margin on palms and soles [5,6]. Clinical features of Vorner's type of PPK are akin to Unna-Thost disease. Differentiation of Vorner’s keratoderma from Unna-Thost disease can be made histopathologically, with the finding of epidermolysis in the former [7].

The main objective of this case reporting is to highlight the two major type of autosomal dominant, non-transgradient palmo-planter keratoderma which look indistinguishable on clinical examination. The histopathological examination holds the key to differentiate between the two.

1. Schiller, S. et al. “Palmoplantar keratoderma (PPK): Acquired and genetic causes of a not so rare disease.”JDDG: Journal der Deutschen Dermatologischen Gesellschaft, vol. 12, no. 9, September 2014, pp. 781–788.

2. Guerra, L. et al. “Hereditary palmoplantar keratodermas. part I: Non-syndromic palmoplantar keratodermas: classification, clinical and genetic features.” Journal of the European Academy of Dermatology and Venereology, vol. 32, no. 5, May 2018, pp. 704–719.

3. Guerra, L. et al. “Hereditary palmoplantar keratodermas. part Ii: Syndromic palmoplantar keratodermas—diagnostic algorithm and principles of therapy.” Journal of the European Academy of Dermatology and Venereology, vol. 32, no. 6, June 2018, pp. 899–925.

4. Dev, T. et al. “Hereditary palmoplantar keratoderma: A practical approach to the diagnosis.” Indian Dermatology Online Journal, vol. 10, no. 4, 2019, pp. 365.

5. Bhat, R. et al. “Unna thost syndrome: A case report.” International Journal of Contemporary Pediatrics, vol. 6, no. 4, June 2019, pp. 1767–1770.

6. Kuster, W. et al. “Epidermolytic palmoplantar keratoderma of vorner: Re-evaluation of vorner’s original family and identification of a novel keratin 9 mutation.” Archives of Dermatological Research, vol. 294, no. 6, June 2002, pp. 268–272.

7. Karadag, A. et al. “A family of Unna-Thost disease with one member showing findings of epidermolytic keratoderma.” Indian Journal of Dermatology, Venereology and Leprology, vol. 76, no. 1, January 2010, pp. 85–85.