History and exam
Key diagnostic factors
common
scaling
The feature that is common to all ichthyoses, including the rarer subtypes, is scale. The character of the scale in patients with autosomal recessive congenital ichthyosis can vary from very fine scaling (congenital ichthyosiform erythroderma) to larger, plate-like scales (lamellar ichthyosis).
Red plaques with double-edged scale, referred to as ichthyosis linearis circumflexa, are a hallmark of Netherton syndrome.[18]
The scale in patients with epidermolytic ichthyosis tends to be corrugated or verrucous.
skin changes at birth (in congenital ichthyosis)
Most inherited ichthyoses present with skin changes at birth.[1]
The autosomal recessive congenital ichthyoses typically present as a collodion membrane or generalized erythema and scaling, whereas epidermolytic ichthyosis typically presents with widespread erythema, erosions, and blistering.
onset in infancy (in ichthyosis vulgaris and X-linked ichthyosis)
Early signs of ichthyosis vulgaris and X-linked ichthyosis, such as fine scaling, typically appear within the first year of life.[1]
adult onset (in acquired ichthyosis)
Acquired ichthyosis typically appears in adulthood.[14]
male sex
X-linked ichthyosis is carried on the X chromosome and only fully expressed by males.[19]
family history of ichthyosis
A positive family history is common in ichthyosis vulgaris and in about 50% of patients with epidermolytic ichthyosis, both of which are inherited in an autosomal dominant fashion.
Other diagnostic factors
common
history of atopy
Symptoms of atopy are common in patients with ichthyosis vulgaris and can include asthma, environmental allergies, and atopic dermatitis.[22] Patients with Netherton syndrome also often have eczematous plaques, allergies, and elevated IgE.
history of lymphoma, diabetes mellitus, systemic lupus erythematosus
Several systemic diseases have been reported in association with acquired ichthyosis, including lymphoma, diabetes mellitus, and systemic lupus erythematosus (SLE).[9][10][11][12]
It is important to ask about symptoms that may indicate these systemic diseases. Lymphomas (both Hodgkin and non-Hodgkin) may present with fevers, night sweats, and weight loss. Diabetes mellitus can present with polyuria, polydipsia, and polyphagia. Symptoms of SLE include fatigue, arthritis, oral ulceration, and photosensitivity.
uncommon
use of clofazimine, lipid-lowering agents, or butyrophenone
alopecia and ectropion in lamellar ichthyosis
The thicker scales that are present in lamellar ichthyosis can lead to other cutaneous features, including ectropion and alopecia.[17]
cryptorchidism and corneal opacities
These may be observed in patients with X-linked ichthyosis.[19]
deafness, intellectual disability, limb defects, epilepsy, short stature
With the rare ichthyoses, such as in Sjogren-Larsson syndrome and Refsum disease, severe organ dysfunction can be observed, including deafness, intellectual disability, limb defects, epilepsy, short stature, and others.
Risk factors
strong
positive family history
Ichthyosis vulgaris (the most common ichthyosis) and other forms of ichthyosis, such as epidermolytic ichthyosis, are inherited in a dominant fashion. Affected patients may, therefore, have an affected parent.
Patients with recessive X-linked ichthyosis often have other male family members with the condition.
parental consanguinity
Many of the more severe types of ichthyoses, including autosomal recessive congenital ichthyosis, and many of the syndromic ichthyoses, are inherited in a recessive pattern. As such, there is a higher frequency of these disorders in consanguineous populations.[5]
weak
use of clofazimine, lipid-lowering agents, or butyrophenone
history of lymphoma, diabetes mellitus, systemic lupus erythematosus
Several systemic diseases have been reported in association with acquired ichthyosis, including lymphoma, diabetes mellitus, and systemic lupus erythematosus (SLE).[9][10][11][12]
It is important to ask about symptoms that may indicate the presence of these systemic diseases. Lymphomas (both Hodgkin and non-Hodgkin) may present with fevers, night sweats, and weight loss. Diabetes mellitus can present with polyuria, polydipsia, and polyphagia. Symptoms of SLE include fatigue, arthritis, oral ulceration, and photosensitivity.
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