The signs and symptoms of IT can be classified according to the type they belong to:
- Ichthyosis vulgaris: In this case the skin might appear normal at birth, but begins to dry developing fine white scale by the age of 5 years. The most affected regions of the body are abdomen, arms and legs. Another typical sign is keratosis pilaris, a very common form of dry skin characterized by the appearance of rough and red bumps on the skin , which is frequently associated with excessively lined palms. Atopic eczema is another classical signs, appearing in 50% of the cases.
- Recessive X-linked ichthyosis: In this type the disorder appears very early in life, within 6 months from birth, with the development all over the skin of fined or rhomboid grey/brown scales. Scaling is most prominent on the extremities as well as neck, trunk and buttocks, while on the contrary to what happens in ichthyosis vulgaris palms appear normal. Other classical signs include corneal opacities and undescended testicles, appearing respectively in 50% and in 5-20% of the cases. The disorder occurs only in males.
- Autosomal recessive congenital ichthyosis-1 (ARCI1): Also appearing very early in life, this type causes the appearance of a collodion membrane, which afterwards cracks. One of the most life-threatening forms is the already mentioned harlequin ichthyosis, where the collodion membrane is very severe and appears together with ectropion (drooping lower eyelids), eclabium (out-turned lips) and contractures. The typical variants include lamellar ichthyosis, characterized by a dark scaling all over the body especially on arms and legs, nonbullous congenital ichthyosiform erythroderma (NCIE), with the scaling appearing as white, superficial and semi-adherent that is frequently accompanied by erythroderma, and palmoplantar keratoderma, which varies based on the gene involved.
- Keratinopathic ichthyoses: The skin appears moist, red, and tender, full of filled blisters which might afterwards become infected and give rise to a foul smell. Scaling is thick, white to brown in color, and appears especially over extensor joints. Growth failure is very frequent among affected individuals, together with the appearance of a general mosaic appearance of the skin. The major variants include epidermolytic ichthyosis, ichthyosis hystrix of Curth-Macklin (IHCM), and the already mentioned palmoplantar keratoderma.
- Acquired ichthyosis: This form is very similar to ichthyosis vulgaris, even though it develops later in life. As previously stated, this form might be the clinical manifestation of an underlying disease such as Hodgkin lymphoma, or the severe side effect of a particular drug.
Marie Lodén, The Use of Urea in the Treatment of Dry Skin, Treatment of Dry Skin Syndrome, 10.1007/978-3-642-27606-4_33, (481-492), (2012). [doi.org]
The most common type of IT is undoubtedly ichthyosis vulgaris accounting for the 95% of the cases, which is mild in nature and frequently mistaken for normal dry skin. [symptoma.com]
‘Severe dry skin is a feature of certain genetic diseases such as atopic dermatitis and ichthyosis (fish scale-like skin).’ Pronunciation [en.oxforddictionaries.com]
Common features of the ichthyoses include thick, dry skin, various forms and degrees of scaling, cutaneous inflammation, hypohidrosis, and skin fragility. [accesspediatrics.mhmedical.com]
The patches of dry skin typically appear on the elbows and lower legs. It most often affects the shins in thick, dark segments. [healthline.com]
Symptoms Dry skin, severe Scaly skin ( scales) Possible skin thickening Mild itching of the skin The dry, scaly skin is usually most severe on the legs. But it can also involve the arms, hands, and middle of the body. [nicklauschildrens.org]
The project in short Sjögren-Larsson Syndrome (SLS) is a rare inborn error of aldehyde metabolism characterized by severe skin thickening (ichthyosis), retinal disease, and neurological dysfunction. [lipotype.com]
Symptoms may include any of the following: Dry skin, severe Scaly skin (scales) Possible skin thickening Mild itching of the skin The dry, scaly skin is usually most severe on the legs. [medlineplus.gov]
Symptoms Symptoms may include any of the following: Dry skin, severe Scaly skin (scales) Possible skin thickening Mild itching of the skin The dry, scaly skin is usually most severe on the legs. [mountsinai.org]
Symptoms Symptoms may include any of the following: Dry skin, severe Scaly skin ( scales ) Possible skin thickening Mild itching of the skin The dry, scaly skin is usually most severe on the legs. [ufhealth.org]
We report a 21-year-old man with recurrent bullous eruptions and severe itching on the lower legs and feet since 5 years of age. Dry, dirty brown, tile-like scales covered his lower legs with dystrophic toenails. [ncbi.nlm.nih.gov]
Similarly in our case, we reported multiple carious teeth, over retained deciduous teeth, delayed eruption of permanent teeth and lingually erupting premolar tooth. [omicsonline.org]
Types: xeroderma, xerodermia a mild form of ichthyosis characterized by abnormal dryness and roughness of the skin xeroderma pigmentosum a rare genetic condition characterized by an eruption of exposed skin occurring in childhood and photosensitivity [vocabulary.com]
Patient's parent gave a history of delayed eruption of his milk teeth. The boy was born to a consanguineous couple as a collodion baby. [ijpd.in]
Allergic contact dermatitis Asteatotic eczema Drug eruptions Harlequin ichthyosis Impetigo Irritant contact dermatitis Lamellar ichthyosis Pediatric atopic dermatitis X-linked ichthyosis. [lecturio.com]
Exfoliation of the Skin
Chronic dermatitis is typical among rare primary ... [centerwatch.com]
The diagnosis of IT is mainly based on the physical examination of the skin. As it is an inherited disorder, a family history of the patient might be useful to detect and classify the disorder. Both approaches can be largely supported by performing a skin biopsy and genetic testing. The presence of systemic disorders such as diabetes mellitus can support the diagnosis of IT .
Subsequently fasting hypoketotic hypoglycemia occurred without permanent hepatomegaly or hyperlipidemia. Continuous gavage feeding was followed by clinical improvement including ichthyosis and hypoglycemia. [ncbi.nlm.nih.gov]
She had not cytopenia. Ultrasonography (US) showed pancreatic diffuse high echogenicity. Subsequently fasting hypoketotic hypoglycemia occurred without permanent hepatomegaly or hyperlipidemia. [ncbi.nlm.nih.gov]
As IT is mainly an inherited disorder, no permanent cure has been developed, and treatment is largely based on palliative approaches. Very common is the application of creams and emollient oils to hydrate the skin, especially those products containing lactic acid which have proved to be exceptionally effective to treat dry skin. Other classes of chemical compounds which appear effective in treating IT include propylene glycol and retinoids. Exposure to sunlight might improve the condition in certain cases, even thought it can have severe side effects, while the use of oral antibiotics to avoid secondary infections is highly recommended.
Other effective measures can include the use of non-soap cleansers, bathing in salt water, rubbing with a pumice stone to remove scales, or the use of vitamin D supplementations, especially in the most severe cases.
As the severity of IT depends on the type taken into consideration, prognosis too varies according to the case. For the majority of the patients who suffer for mild forms of IT, topical therapy is already sufficient and generally they do well after treatment. On the contrary, prognosis is not good in the most severe forms involving major systemic disorders, where the skin is only the minor clinical concern for the patients.
For example, prognosis is very good with ichthyosis vulgaris, where the major concern is skin moisturization, but not with X-linked ichthyosis, where patients are at higher risk to develop testicular cancer, a far more lethal disorder than IT itself.
The formation of epidermis is the result of an intricate interaction among several components, such as intracellular and extracellular proteins, lipids, nuclear filaments, and key enzymes, each one of them playing a pivotal role in skin development. Any defects in one of this component might be catastrophic and can lead to the occurrence of IT. Although generally inherited, some forms of IT can be acquired. These are usually caused by certain medications, including some of frequent use such as clofazimine, lipid-lowering agents, and butyrophenone   . It should be noted that several important systemic disorders, such as lymphoma   or diabetes mellitus , might also cause IT.
The major genes and proteins involved in IT include:
- Filaggrin: A filament-associated protein which plays an important role in epidermal homeostasis by binding to keratin fibers in epithelial cells.
- Keratins: A group of fibrous structural proteins representing one of the major components of cytoskeleton.
- ATP-binding cassette transporter 12: Transmembrane proteins using the energy coming from ATP molecules to perform key biological processes such as substrates translocation, RNA translation and DNA repair  .
- Steroid sulfatase: Sulfatase enyme with a pivotal role in steroids metabolism, found in great abundance as monomer in the endoplasmic reticulum.
- Ceramide synthases: Integral membrane proteins involved in the synthesis of ceramide (an important membrane component) in the endoplasmic reticulum .
The incidence and prevalence of IT vary according to the type considered as well as the population under investigation. For instance, prevalence of ichthyosis vulgaris has been estimated to be around 1 case every 250 individuals in UK  and around 2 cases every 100 individual in China . The prevalence of the other less frequent forms is lower, on average around 1 case every 300,000 individuals .
As previously said, the underlying cause of the IT clinical manifestations is the genetic mutations on the genes playing a pivotal role in skin development, which result in a marked increase of keratinization. The major clinical manifestation is undoubtedly the presence of scales all over the skin of the affected person, whose size and thickness vary according to the particular type of IT considered. The degree of scaling is an important pathological factor in itself, as it might cause or extensively influence other important clinical manifestations such as erythema, pruritus, bacterial colonization, and hair loss. Furthermore, as these mutated genes and proteins might play an important role for the entire body, they can frequently cause systemic clinical manifestations.
IT is a chronic condition which requires a lifelong treatment. Therefore, any of the previously indicated measures should be performed permanently during the entire course of the patient’s life, especially to avoid major side effects such as chronic water loss or dangerous skin infection, which might severely affect the quality of life in adults and impair growth and development in children.
The name ichthyosis (IT) derives from the Greek word ἰχθύς (ichthys) meaning fish, with clear reference to the fishy resemblance of the skin of the people affected. The severity of this disorder varies very much, according to the type taken into consideration. The most common type of IT is undoubtedly ichthyosis vulgaris accounting for the 95% of the cases  , which is mild in nature and frequently mistaken for normal dry skin. By contrast, one of the most life-threatening forms is harlequin type ichthyosis, which causes the skin to thicken and frequently results in fatal infections.
These skin disorders are the result of the presence of excessive amounts of dry surface scales due to marked keratinization or cornification, as a consequence of abnormal epidermal differentiation and metabolism. To date, five major types of IT have been officially described, which include ichthyosis vulgaris, lamellar ichthyosis, epidermolytic hyperkeratosis, congenital ichthyosiform erythroderma, and X-linked ichthyosis. These can be differentiated based on the general clinical manifestations, histological findings, as well as genetic makeup .
Ichthyosis (IT) is a term referring to at least 28 different genetic skin disorders, where the skin predominantly appears dry, thickened, scaly and cracked. The name of this group of disorders comes from the Greek word ἰχθύς (ichthys) meaning fish, with clear reference to the fishy resemblance of the skin. This disorder originates from one or more defects in skin development, which might have catastrophic consequences in terms of abnormal clinical manifestations.
There are 5 major types of IT: Ichthyosis vulgaris (the most common of the five), recessive X-linked ichthyosis, autosomal recessive congenital ichthyosis-1 (ARCI1), keratinopathic ichthyoses, and acquired ichthyosis. Each one of these has its own particular repertoire of clinical manifestations, the most common of which include dry skin, rough and red bumps on the skin, atopic eczema, scales, corneal opacities and collodion membrane.
As IT is mainly an inherited disorder, no permanent cure has been developed, and treatment is largely based on palliative approaches. Very common is the application of creams and emollient oils to hydrate the skin, especially those products containing lactic acid which have proved to be exceptionally effective to treat dry skin. Other effective measures can include the use of non-soap cleansers, bathing in salt water, rubbing with a pumice stone to remove scales, or the use of vitamin D supplementations, especially in the most severe cases. IT is a chronic condition which requires a lifelong treatment. Therefore, any of the previously indicated measures should be performed permanently during the entire course of life, especially to avoid major side effects such as chronic water loss or dangerous skin infection.
- Okulicz JF, Schwartz RA. Hereditary and acquired ichthyosis vulgaris. International Journal of Dermatology 2003 42 (2): 95–8.
- Moeschler JB, Shevell M. Clinical genetic evaluation of the child with mental retardation or developmental delays. Pediatrics. Jun 2006;117(6):2304-16.
- Caver CV. Clofazimine-induced ichthyosis and its treatment. Cutis. 1982;29:341-343.
- Williams ML, Feingold KR, Grubauer G, et al. Ichthyosis induced by cholesterol-lowering drugs: implications for epidermal cholesterol homeostasis. Arch Dermatol. 1987;123:1535-1538.
- Kutting B, Traupe H. Acquired ichthyosis-like skin disease: a challenge for diagnostic evaluation. Hautarzt. 1995;46:836-840.
- Ghislain PD, Roussel S, Marot L, et al. Acquired ichthyosis disclosing Hodgkin's disease: simultaneous recurrence. Presse Med. 2002;31:1126-1128.
- Tamura J, Shinohara M, Matsushima T, et al. Acquired ichthyosis as a manifestation of abdominal recurrence of non-Hodgkin's lymphoma. Am J Hematol. 1994;45:191-192.
- Scheinfeld N, Libkind M, Freilich S. New-onset ichthyosis and diabetes in a 14-year-old. Pediatr Dermatol. 2001;18:501-503.
- Davidson AL, Dassa E, Orelle C, Chen J. Structure, function, and evolution of bacterial ATP-binding cassette systems. Microbiol. Mol. Biol. Rev. 2008 72 (2): 317–64, table of contents.
- Goffeau A, De Hertogh B, Baret PV. 2004. ABC Transporters. In: Encyclopedia of Biological Chemistry. Vol. 1, 1–5.
- Levy M, Futerman AH. Mammalian ceramide synthases. IUBMB Life 2010 62 (5): NA–NA.
- Wells RS, Kerr CB. Clinical features of autosomal dominant and sex-inked ichthyosis in an English population. Br Med J. 1966;1:947-950.
- Lei G, Zhang Y, Hu Y. Investigation on the prevalence of ichthyosis in Sichuan province. Chin J Dermatol. 1992;25:105-106.
- Al-Zayir AA, Al-Amro Al-Alakloby OM. Clinico-epidemiological features of primary hereditary ichthyoses in the Eastern province of Saudi Arabia. Int J Dermatol. 2006;45:257-264.
- Panchaprateep R, Tanus A, Tosti A. Clinical, dermoscopic, and histopathologic features of body hair disorders. Journal of the American Academy of Dermatology. 2015 S0190-9622 (15): 00089–4.
- Scheinfeld N, Libkind M, Freilich S. New-onset ichthyosis and diabetes in a 14-year-old. Pediatric dermatology 2001 18 (6): 501–3.