Dermatology · Mal de Meleda

Diagnosis, Genetics, and Look-Alikes

At a Glance

Mal de Meleda is usually recognized by the pattern of thickened skin spreading from the palms and soles, then clarified with genetic testing, especially for SLURP1 changes. A negative result or uncertain variant does not automatically rule out the clinical diagnosis.

The process of diagnosing transgrediens et progrediens palmoplantar keratoderma (Mal de Meleda) involves piecing together the physical symptoms, the family history, and the underlying genetic blueprint. Mal de Meleda is often recognized clinically by a dermatologist based on how the skin looks and behaves, with genetic testing used to confirm the diagnosis, determine inheritance, and distinguish it from very similar conditions ^[1]^[2].

The Genetic Blueprint

Classic Mal de Meleda is an autosomal recessive condition caused by mutations in the SLURP1 gene ^[3]. This gene provides instructions for making a protein that helps regulate how skin cells grow and mature ^[4]^[5]. When this gene is mutated, the skin’s normal shedding process is disrupted ^[6].

While SLURP1 is the established cause of classic Mal de Meleda, researchers have identified other genes that can cause similar-looking “transgredient” patterns. Mutations in genes like SERPINA12, CDH12, or CTSB are considered rare phenocopies or differential diagnoses that create atypical presentations overlapping with Mal de Meleda ^[7]^[8]^[9].

How the Diagnosis is Reached

Your medical team typically uses clinical assessment alongside specialized testing to understand your condition:

Clinical Evaluation: A dermatologist will examine the distribution of the thickened skin, looking specifically for the “transgrediens” spread and the “progrediens” progression ^[4].
Genetic Testing: A multi-gene panel or whole-exome sequencing is recommended when available to find specific mutations ^[2]^[10]. Genetic testing results can be:
- Pathogenic/Likely Pathogenic: Confirms the specific genetic cause.
- Negative: Does not necessarily rule out a clinical diagnosis of a palmoplantar keratoderma, but means the specific gene was not identified.
- Variant of Uncertain Significance (VUS): A genetic change was found, but there is not enough evidence to know if it causes the disease. This is not a confirmed diagnosis.
Skin Biopsy: While not always required, a small sample of skin may be taken for a microscope examination (histopathology). In Mal de Meleda, this typically shows hyperkeratosis (extreme thickening of the outer layer) and acanthosis (thickening of the middle layer), and a “lack of epidermolysis” ^[4]^[11]. Note that “epidermolysis” here refers to a specific microscopic pattern of cells breaking down (epidermolytic hyperkeratosis), not the ordinary clinical blistering of the skin.

Distinguishing the “Look-Alikes”

Because many rare skin conditions cause thickened palms and soles, Mal de Meleda is often compared to several “look-alike” conditions.

Condition	Key Distinguishing Features	Genetic Cause
Nagashima-type PPK	Usually milder and non-progressive (does not worsen much over time). ^[12]	SERPINB7 gene
Vohwinkel Syndrome	Features unique “starfish-shaped” lesions on the knuckles. Certain variants are associated with hearing loss (typically those involving the GJB2 gene, whereas LOR-related disease is a distinct variant without hearing loss). ^[13]	GJB2 or LOR gene
Olmsted Syndrome	Can be very severe and painful, often affecting the skin around the mouth and eyes (periorificial). ^[14]	TRPV3 or MBTPS2 gene
Bothnian PPK	Features a unique “hand-in-the-bucket” sign, where the skin becomes very white and spongy immediately after touching water. ^[15]	AQP5 gene

By using genetic testing alongside clinical observation, your care team can provide more accurate information about the disease and risks for other family members ^[16]^[17].

Common questions in this guide

What causes Mal de Meleda?

Classic Mal de Meleda is usually caused by disease-causing changes in both copies of the SLURP1 gene, following an autosomal recessive inheritance pattern. SLURP1 helps regulate how skin cells grow, mature, and shed. Changes in other genes, including SERPINA12, CDH12, or CTSB, can produce a similar pattern but are not classic Mal de Meleda.

How is Mal de Meleda diagnosed?

Diagnosis usually starts with a dermatologist examining the pattern and progression of thickened skin on the palms and soles and reviewing the family history. A multigene panel or whole-exome sequencing can look for the genetic cause. A skin biopsy may be used when the diagnosis remains uncertain or a similar condition needs to be considered.

What does a negative or uncertain genetic test mean for Mal de Meleda?

A negative test means that the tested genetic cause was not found; it does not necessarily rule out a clinical diagnosis of palmoplantar keratoderma. A variant of uncertain significance is a genetic change whose effect is not known, so it is not proof that the variant causes the condition. A genetics professional or dermatologist should interpret the result with your clinical findings and family history.

How can Mal de Meleda be distinguished from similar keratodermas?

Nagashima-type palmoplantar keratoderma is often milder and does not progressively worsen. Vohwinkel syndrome may cause starfish-shaped knuckle lesions and, in some genetic forms, hearing loss; Olmsted syndrome can be painful and affect skin around the mouth and eyes. Bothnian palmoplantar keratoderma can cause white, spongy skin after water exposure.

When is a skin biopsy needed for suspected Mal de Meleda?

A biopsy is not always needed because the skin pattern, course, family history, and genetic testing may provide enough information. If performed, it typically shows marked thickening of the outer skin layer and thickening of a deeper skin layer, without the microscopic pattern called epidermolysis. The dermatologist decides whether a biopsy would help distinguish Mal de Meleda from another condition.

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Key takeaways

Clinical examination of thickened skin and its transgrediens and progrediens pattern, together with family history, supports a Mal de Meleda diagnosis.
Classic Mal de Meleda is caused by autosomal recessive SLURP1 mutations, while changes in other genes can produce similar-looking conditions.
A multigene panel or whole-exome sequencing may identify the genetic cause, but a negative result does not necessarily exclude palmoplantar keratoderma and a variant of uncertain significance is not a confirmed cause.
A skin biopsy is not always required but may show hyperkeratosis, acanthosis, and a lack of the microscopic pattern called epidermolysis.
Nagashima-type, Vohwinkel, Olmsted, and Bothnian palmoplantar keratodermas have distinguishing features that help clinicians compare them with Mal de Meleda.

References (17)

1
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2
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5
Patient with Mal de Meleda in whom a Novel Gene Mutation was Identified.
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Human Secreted Ly-6/uPAR Related Protein-1 (SLURP-1) Is a Selective Allosteric Antagonist of α7 Nicotinic Acetylcholine Receptor.
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7
Identification of a CDH12 potential candidate genetic variant for an autosomal dominant form of transgrediens and progrediens palmoplantar keratoderma in a Tunisian family.
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PMID: 31911611
8
Palmoplantar keratoderma caused by a missense variant in CTSB encoding cathepsin B.
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9
The Proteolytic Network in Palmoplantar Keratoderma: SERPINA12 Joins the Family.
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10
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11
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12
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13
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14
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15
Bothnian Palmoplantar Keratoderma: Further Delineation of the Associated Phenotype.
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16
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17
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This page explains Mal de Meleda diagnosis and genetics for informational purposes only and does not constitute medical advice. A dermatologist or genetics professional should interpret your examination and test results.