Palmoplantar keratoderma, Nagashima type

This symptom manifests as a noticeable thickening of the skin on the palms of the hands and soles of the feet. The biological mechanism involves mutations in the SERPINB7 gene, leading to abnormal keratinization. Over time, the thickening may become more pronounced and can lead to fissures or cracks. This affects daily life by causing discomfort or pain during activities such as walking or grasping objects, and regular moisturizing and keratolytic agents can help manage it.

Hyperkeratosis presents as an excessive buildup of keratin on the skin surface, leading to a rough texture. It is caused by an overproduction of keratin due to genetic mutations affecting skin cell turnover. The condition can worsen with age or environmental factors like friction. Patients may experience difficulty in performing manual tasks, and treatments include topical retinoids or salicylic acid to reduce skin thickness.

Fissuring occurs when the thickened skin on the palms and soles cracks, creating painful splits. This happens due to the rigidity and reduced elasticity of hyperkeratotic skin. Without intervention, fissures can deepen and lead to secondary infections. Daily activities such as walking or handling objects can become painful, and management involves keeping the skin well-moisturized and protected.

Redness and inflammation are often seen around areas of thickened skin, indicating underlying irritation. This results from the body's immune response to the abnormal skin barrier. Over time, inflammation can lead to further skin damage if not managed. It can cause discomfort and itching, and anti-inflammatory treatments such as topical corticosteroids may be used.

Pain is a common symptom due to the pressure and tension on thickened skin, especially during movement. It arises from nerve irritation and micro-tears in the skin. The intensity of pain can increase with physical activity or prolonged standing. Pain management includes the use of analgesics and protective padding to reduce pressure.

Blistering may occur in response to friction or pressure on the thickened skin areas. This is due to the separation of skin layers caused by weakened structural integrity. Blisters can become more frequent with increased physical activity. They can lead to discomfort and potential infection, so protective footwear and blister care are recommended.

Nail abnormalities can include thickening, discoloration, or ridging of the nails. These changes occur due to the same keratinization defects affecting the skin. Over time, nail changes can become more pronounced and affect nail growth. They may cause cosmetic concerns and discomfort, and treatment focuses on regular nail care and monitoring.

Itching is a less common symptom but can occur due to dry and irritated skin. It is caused by the release of inflammatory mediators in response to skin barrier disruption. Persistent itching can lead to scratching and further skin damage. Antihistamines and emollients can be used to alleviate itching and protect the skin.

Clinicians look for thickened, hyperkeratotic skin on the palms and soles, often with a yellowish hue. A detailed family history is crucial, as the condition is inherited in an autosomal recessive manner. Physical examination reveals symmetrical involvement of the palms and soles, sometimes extending to the dorsal surfaces. This step helps differentiate Nagashima-type from other forms of keratoderma.

Imaging studies are not typically used in the diagnosis of Nagashima-type palmoplantar keratoderma. However, if performed, high-resolution ultrasound might show thickened stratum corneum. These findings can support the diagnosis but are not definitive. Imaging helps exclude other conditions with similar presentations, such as plantar fibromatosis.

Routine laboratory tests are not specific for this condition, but skin biopsy can be performed. Histopathology may reveal hyperkeratosis and acanthosis. These results are non-specific but can rule out other dermatological conditions. Laboratory findings guide the clinician toward genetic testing for confirmation.

Genetic testing focuses on sequencing the SERPINB7 gene. Mutations such as missense or nonsense mutations in this gene confirm the diagnosis. Identification of these mutations provides a definitive diagnosis and informs genetic counseling for the family. This step is crucial for understanding inheritance patterns and recurrence risks.