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Animals in Dermatology

2024; Medknow; Linguagem: Inglês

10.4103/ijd.ijd_502_23

1998-3611

Vishalakshi S. Pandit, R. Rakesh Yelhanka,

Vector-borne infectious diseases

Dermatology is a vast subject which needs immense learning and understanding. Studies have shown that visual memory is superior to the auditory memory. Many of the clinical findings have been compared to animal parts or shapes for the ease of understanding and to make the subject more interesting and visually appealing. So, this is an attempt to group out such diseases and findings named after a few animals. Buffalo hump: seen in long-term steroid administration, HIV/HAART associated lipodystrophy syndrome due to fat redistribution in the dorso-cervical region. Bull's eye appearance: Erythema migrans is an erythematous, expanding annular plaque with a lighter-coloured central area, which typically develops 7–15 days after the detachment of Borrelia-infected tick. The advancing edge may be crusted or even vesicular. Common sites of involvement are trunk and flexures.In erythema multiforme, the classical elementary lesion has two concentric rings of colour change surrounding a central circular zone that has damage to the epidermis in the form of bulla or crust formation [Figure 1].'Cowboy gunbelt and holster': Configuration of sclerotic lesions with lilac-coloured borders on the buttocks and thighs resemble this pattern in Texier's disease, panniculitis due to phytonadione (vitamin K) injections.[1] 'Dog-faced' hypertrichosis lanuginosa: Entire skin is covered by silky hair, which may be 10 cm or longer with long eyelashes and thick eyebrows[2] [Figure 2]. Elephant skin: In chronic onchocerciasis, the skin becomes thickened and wrinkled; this is accompanied by lichenification and hyperpigmentation, which resembles the skin of an elephant.[3] Elephantine psoriasis: It is an uncommon form of psoriasis characterized by thickly scaling and large plaques, usually on the lower extremities. Elephantiasic variant: An extreme form of diffuse thyroid dermopathy, characterized by progressive thickening and grey-black hyperpigmentation of the pretibial skin accompanied by a woody, firm oedema with nodule formation. It occurs in less than 1% of patients with Graves' disease.[4] Tree-frog appearance: The short, club-shaped terminal phalanges give this appearance in familial mandibuloacral dysplasia.[5] Frog-spawn appearance: This is seen in grouped, fluid-filled vesicles of lymphangioma circumscriptum [Figure 3]. Fish odour syndrome (trimethylaminuria): Excessive amounts of the offensively smelling tertiary amine trimethylamine appear in both eccrine and apocrine sweat, breath and urine, which imparts an unpleasant rotting fish smell to sufferers.[6] Conditions which impart fishy odour are mentioned in Table 1. The term 'ichthyosis' derived from the Greek root 'ichthys' meaning fish was introduced by William in his dermatological textbook in 1808.[9] The term is used to describe a group of keratinization disorders characterized by fish-like scaly skin [Figure 4]. Starfish-like hyperkeratoses: It is seen in Ichthyosis hystrix Curth–Macklin, Vohwinkel syndrome. The hyperkeratosis is present at birth or develops during early childhood over knuckles. Other associated features seen in Vohwinkel syndrome include pseudo-ainhum, honeycomb palms and deafness.[9] 'Fish-mouth' appearance: The appearance of a gaping wound gives this appearance in Ehlers-Danlos syndrome. The skin is fragile, particularly over pressure points, shins and forehead.[10] Fishnet-like pattern: In livedo reticularis, a symmetric, fishnet-like red or purple mottling surrounds a pallorous conical core [Figure 5]. Commonly seen on lower legs, aggravated by cold and disappears on warming.Direct immunofluorescence of pemphigus vulgaris demonstrates intercellular IgG deposits in the epidermis in the fishnet-like pattern.'School-of-fish' appearance: Gram-stained smear from the exudates of chancroid show short chains of Gram-negative bacilli, Haemophilus ducreyi giving an appearance of 'school of fish'. Also known as the 'railroad track' pattern. Horse-riding stance: Skeletal abnormalities such as dystrophic clavicle, coxa valga with joint contractures, narrow chest and protuberant abdomen owing to a mild flexion of the knee give this appearance in progeria.[11] Horse-collar pattern: Symmetrical distribution of large, masses of fat around the neck and shoulder region in multiple symmetrical lipomatosis.[12] Horse rider's pernio ('equestrian panniculitis'): Cold panniculitis, an inflammatory reaction occurring in equestrians (horse-riding enthusiasts) following exposure to cold. Perniosis occurs on the outer thighs of horse riders, who use tight-fitting trousers such as riding breeches.[13] 'Horseshoe-shaped' rim of hair [Figure 6]: A u-shaped pattern on the scalp is observed in type 7 of Hamilton-Norwood classification for androgenetic alopecia.[14] In this male pattern baldness, hair follicles are present in a horseshoe band that begins just anterior to ear extending posteriorly onto the sides and the low occiput area. Table 2 shows conditions with horse-shoe shaped configurations. Leonine facies: Certain diseases sometimes infiltrate the face to cause a 'lion-like' appearance, with thickening and furrowing. Condition presenting with leonine facies is lepromatous leprosy [Figure 7]; others are mentioned in Table 3. Leopard skin: In onchocerciasis, initially, small (punctuate), yellow–brown, hypomelanotic macules appear on the middle third of the shin medial to the tibial crest. Later, the macules enlarge, coalesce and undergo progressive lightening until there is amelanosis. Atrophy and a loss of pigment with sparing perifollicular skin are also seen in late-stage onchocerciasis. Pigmented islets persist within the hypopigmented patches, hence the designation 'leopard skin' for these changes.[16] Leopard-like appearance: In Ziprkowski–Margolis syndrome, diffuse pigmentary dilution of the hair and skin is seen, sparing the buttocks and genital region. Later, multiple hyperpigmented macules appear, giving the skin a leopard-like appearance.[17] Leopard syndrome: The acronym refers to lentigines, electro-cardiographic conduction defects, ocular hypertelorism, pulmonary stenosis, abnormalities of genitalia, retardation of growth and deafness.[18] Mauskopf facies: The shiny, taut expressionless face and pinched nose with a beak-like appearance seen in systemic sclerosis.[19] Monkey facies: The skin loses turgor and becomes wrinkled and loose as subcutaneous fat disappears. This facial expression is due to loss of buccal adipose tissue seen in marasmus.[20] Monkey face: In congenital hypertrichosis lanuginosa, the fine, silvery-grey to blond hair continues to grow, reaching lengths of up to 10 cm and covering the entire body surface except for the palms, soles, dorsal surface of the distal phalanges, and prepuce. The hair growth is said to lead to a 'dog' or 'monkey' face.[21] 'Pigskin' appearance: pebbly firm plaque, slightly depressed, follicular openings of the shagreen patch of tuberous sclerosis [Figure 8]. Commonly seen in lower back.[22] Rabbit burrow appearance: Epithelioma cuniculatum appears on the soles, arising from a plantar wart. Crevices appear in these lesions giving a rabbit burrow appearance.[23] 'Rabbit lines': Skin tension lines exaggerated by wrinkling up the nose. The procerus muscle overlies the nasal bone and attaches to the nasal root skin. It causes foreshortening of the nose and rabbit lines.[24] Rat-bite fever: Streptobacillus moniliformis infections following a rat bite result in an acute illness characterized by fever, arthritis and a rash. The rash is characterized by an acrally distribution eruption involving the palms and soles; Morbilliform macules and papules, petechiae, vesicles and crusts may all be seen.[25] Rat-tail macroconidia: Trichophyton schoenleinii has glabrous colonies, antler and nailhead hyphae and rat-tail macroconidia. Tiger tail hair: Hair in trichothiodystrophy is sparse, short, brittle and uneven; the scalp hair, eyebrows or eyelashes may be affected. Polarizing light microscopy of the hair reveals the characteristic light and dark bands. Toad skin: The keratotic follicular papules seen on the extremities and trunk in vitamin A deficiency are often referred to as phrynoderma (In Greek: toad skin).[26] Zebra-stripe pattern: Also seen in inflicted immersion burns (a method of child abuse) involving buttocks, lower back and thighs. The child is flexed at the waist and dipped into the hot water, frequently as a punishment for a toilet training accident. The resultant pattern may give 'zebra stripes' on the abdomen due to sparing of the flexural skin that is protected from the scald when bent forward.[27] Other conditions presenting with zebra-stripe patterns are shown in Table 4. Lesions have a wood-grain or zebra-like pattern, due to the development of 'rings within rings' seen in erythema gyratum repens.[30] Zebra bodies: Intracytoplasmic, electron-dense, vacuolar inclusion bodies in endothelial cells and fibroblasts are seen under electron microscopy of angiokeratoderma of Fabry disease. Turkey ear: It is a clinically descriptive term, used for a massively enlarged earlobe with bluish-red or violaceous indurated plaques and nodules, which can be a sign of lupus vulgaris. It can also be seen in lupus pernio (sarcoidosis).[31] Sea anemone: Dermoscopic features of black hairy tongue are seen as yellowish-brown and brownish-black hair-like projections (elongated filiform papillae) in aggregates resembling "sea anemone" with interspersed white structureless areas over a pinkish background.[32] Figure 1: Target or iris lesion: contains three zones of colour change in erythema multiforme. (Target reprinted with the permission from pixabay.com)Figure 2: Face is covered with long silky hair with long eyelash and eyebrows giving an appearance of dog-faced in congenital hypertrichosis lanuginosa. (Dog face reprinted with the permission from pixabay.com)Figure 3: Discreet or grouped vesicles of lymphangioma circumscriptum on scrotum resembling frog spawn. (Frog spawn image reprinted from twinkl.co.in/teaching-wiki)Figure 4: Large, dark, quadrilateral scale resembling fish-like scale in lamellar ichthyosis. (Fish scales reprinted from Rajesh Dangi at English Wikipedia)Figure 5: Reddish blue mottled and blotchy discolouration of skin in a fishnet pattern seen in livedo reticularis. (Fishnet reprinted with the permission from pixabay.com)Table 1: Conditions imparting with fishy-odourTable 2: Conditions with horseshoe-shaped configurationsTable 3: Conditions presenting with leonine faciesFigure 6: Horseshoe shaped rim of hair around the scalp in androgenetic alopecia. (Horseshoe reprinted with the permission from pixabay.com)Figure 7: Massive infiltration of face with prominent ridges and furrows and loss of eyebrows giving lion-like face appearance in lepromatous leprosy. (Lion face reprinted with the permission from pixabay.com)Table 4: Conditions with features of zebra-stripe patternFigure 8: Skin-coloured, raised, irregular thickening with multiple follicular openings of shagreen patch resembling pigskin. (Dark-coloured pigskin on right side reprinted with the permission from pixabay.com)Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.