Unstble psoriasis in down’s syndrome

OR Mariyath¹ , J Pinto²

¹ Department of Skin and STD, Kasturba Medical College and Hospital, Attavar, Mangalore, India
² Department of Skin & STD, Wenlock District Hospital, Mangalore-575 001, India

Correspondence Address:
J Pinto
Department of Skin & STD, Wenlock District Hospital, Mangalore-575 001
India

Introduction

Down′s syndrome is the commonest chromosomal disorder and a major cause of mental retardation. It is a multisystem disorder that occurs once in 700 live births.[1] It is associated with an increased chance of congenital heart disease (40-60%), hematological malignancy (20 times more) duodenal atresia, annular pancreas and Hirschsprung′s disease. Adult patients can develop obesity, skin infections, psychiatric disorders, cataract, hypothyroidism, mitral valve prolapse, hearing loss and Alzheimer′s disease. In the absence of a severe cardiac anomaly which leads to early death in 15-20% cases; life expectancy is good.[1]

Cutaneous manifestation in Down′s syndrome are xerosis (85%), tinea pedis (76%), onychomycosis (67%), atopic dermatitis (56%), syringoma (39%), seborrheic dermatitis (36%), acne vulgaris (10%), alopecia areata (9%) cutis marmorata (8%), vitiligo, norwegian scabies, elastosis perforans serpiginosa, malassezia folliculitis, psoriasis and lichen planus.[2]

Case Report

A 19-year-old mentally retarded male presented with itchy, red, raised lesions all over the body of 1 year duration with history of remissions and exacerbations. There was no history of fever, drug intake, joint pain or history of similar illness or mental retardation in the family.

The patient was obese and short statured. There were brachycephaly with flat occiput, Mongoloid facies-upward slanting palpebral fissures, small mouth with protruding tongue, small round ears with angular overlapping helix, short broad neck. Left eye showed strabismus and keratoconus showed scrotal tongue, abnormal size, shape and alignment of teeth. There were short broad hands, clinodactyly and syndactyly, shortening of lower extremities, wide gap between 1st and 2nd toes, deep plantar crease between 1st and 2nd toes dysplastic nipple, small penis and straight public hair.

Systemic examination did not showing abnormality revealed multiple well defined, erythematous, scaly papules and plaques on the scalp, face, ears, trunk and extremities with sparing of palms and soles. There was extension of psoriatic plaques into the neck, axillae and groins. Koebnerisation was present, Auspitz sign was positive. Nails showed subungual hyperkeratosis, distal onycholysis of all fingers and toe nails. Generalised xerosis of the skin was present.

There were multiple, discrete, skin coloured, bilaterally symmetrical papules in the infraorbital regions suggestive of syringoma. Axillae and neck showed dirty brown plaques indicative of acanthosis nigricans.

Diagnosis of Down′s syndrome with unstable psoriasis, syringoma and pseudoacanthosis nigricans was made from the typical clinical features.

Discussion

Psoriasis is a multifactorial disorder caused by the concerted action of multiple disease genes in a single individual triggered by environmental factors.[3] Type 1 psoriasis is characterized by HLA association (CW6 and DR7) and age of onset before 40 yrs. Type II psoriasis lacks HLA association and has an onset beyond 40 yrs with a peak at 60 yrs in females and 57 yrs in males.4 Various datas indicate that psoriasis may be a T cell mediated autoimmune disease leading to abnormal keratinocyte proliferation.[5]

Psoriasis is associated with decreased cyclic adenosine monophosphate (cAMP) and increased cyclic guanosine monophosphate (cGMP). It has been suggested that cell proliferation is stimulated either by a fall in cAMP or by an increase in cGMP. Exacerbation of psoriasis by lithium, and betablockers can also be explained by the same mechanism of inhibition of adenylate cyclase leading to decreased c AMP.

(ATP-adenosine triphosphate, cAMP-Cyclic adenosine monophophate, 12 HETE - 12 hydroxy eicosa tetraenoic acid)

Down′s syndrome or trisomy 21 is a chromosomal disorder which shoes T cell dysfunction, autoimmune disorders and various biochemical abnormalities.[2] One of the biochemical abnormality is decreased c AMP & increased c GMP.[6] Cyclic GMP is formed from GTP by the action of guanylate cyclase. Guanylate cyclase has been suggested to be stimulated by an enzyme superoxide dismutse I (SODI)[7]. The gene responsible for the synthesis of this enzyme is located in the same region of chromosome 21 as that of Down′s syndrome (band 21q 22). The enzymatic activity is increased by a ratio of 3:2 due to triplication of 21st chromosome in Down′s syndrome.[1]

(GTP-guanosine triphosphate, c GMP-Cyclic guanosine monophosphate, SODI-Superoxide dismutaseI)

Down′s syndrome shows features of accelerated aging. Aging is also associated with decreased c AMP and increased c GMP. According to free radical theory, again results from the cumulative damage to tissues by free radicals formed in them. Guanylate cyclase can be activated by free radicals causing increased c GMP.[6]

Thus Down′s syndrome, psoriasis and senility show common alteration in cyclic nucleotides ( c AMP & c GMP). A probable explanation for accelerated aging and early age of onset of psoriasis in Down′s syndrome can be these biochemical abnormalities. However further studies are required to confirm this.

Although psoriasis is common in Down′s syndrome only few cases are reported. This case is reported to point out the importance of biochemical defects in psoriasis and its possible relationship with Down′s syndrome and senility.

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