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Biomedical subjects

B P Khoo

Publications and source records attributed to B P Khoo.

15 recordsLinked to original sources

Dapsone hypersensitivity syndrome masquerading as a viral exanthem: three cases and a mini-review.

INTRODUCTION: We report 3 cases of dapsone hypersensitivity syndrome due to anti-malarial chemoprophylactic treatment with maloprim, in military servicemen, presenting like a viral exanthem. CLINICAL PICTURE: Three male military recruits presented with fever and rash, 6 to 8 weeks after commencing on weekly doses of maloprim. TREATMENT: A course of topical and systemic corticosteroids and oral antihistamines were started. OUTCOME: All cases showed gradual resolution of fever, rash and eventual normalisation of liver function test. CONCLUSION: A high index of suspicion was required before this uncommon syndrome can be recognised. Early institution of corticosteroid therapy and discontinuation of maloprim are the mainstays of treatment.

Adolescent↗

Lichen amyloidosus: a bullous variant.

INTRODUCTION: Lichen amyloidosus is a common skin disease seen among Asian patients. CLINICAL PICTURE: Typical features range from macular hyperpigmentation to pruritic, lichenified, hyperpigmented papules. However, in this rare bullous variant of lichen amyloidosus, bullae and vesicles are present. Histopathologically, deposits of amyloid were seen in the papillary dermis, associated with an intraepidermal or subepidermal blister. TREATMENT AND OUTCOME: No good treatment so far, but pruritus can be relieved by topical steroid. CONCLUSION: It is important to screen for systemic amyloidosis with the relevant investigations as it can present similarly with blistering eruptions, in which the prognosis would be grave.

Adult↗

A review of inpatients with adverse drug reactions to allopurinol.

Allopurinol is still an effective uric-acid lowering drug since its introduction in 1963. However it has been frequently incriminated for severe adverse drug reactions. From our retrospective review of 13 inpatients with allopurinol adverse reactions seen over 3 years, fever and rash were the commonest presenting symptoms, occurring several weeks after initiation of the drug. Other associated abnormalities included leukocytosis (62% of patients), eosinophilia (54%), renal impairment (54%) and liver dysfunction (69%). Although 12 patients (92%) met the criteria for allopurinol hypersensitivity syndrome, there was no mortality recorded. The indications for initiating allopurinol therapy were frequently unclear. In view of the severe adverse reactions experienced with allopurinol, we propose that it should only be prescribed when truly indicated.

Adult↗

A pilot study on the role of intralesional triamcinolone acetonide in the treatment of pitted nails in children.

BACKGROUND: Pitted nails is a non-specific entity seen in children that is often associated with various underlying skin disorders such as atopic dermatitis, psoriasis, alopecia areata and lichen planus; and those without such associations are labelled as idiopathic pitted nails. Spontaneous resolution is common but may take several years. Treatment options so far have not been encouraging. This pilot study sought to determine the safety and efficacy of intralesional steroid in the treatment of pitted nails in children. METHOD: Children with pitted nails below the age of 12, seen between January 1994 and December 1997, were invited to participate in this study. Symmetrically affected fingernails were selected, topical anaesthetic cream applied and a single dose of triamcinolone acetonide was introduced intralesionally to the proximal nailfold while the contralateral nail acted as control. The degree of pitting of nail surface was documented at months 0, 2 and 4. RESULTS: Four children were enrolled, and their ages ranged from 4 to 9 years. The degree of pitting was reduced to a mean of 15% of the nail surface in the second month, and 42% in the fourth month. The procedure was fairly well tolerated and no adverse effects were noted. CONCLUSION: Intralesional steroid is a safe and acceptable method of treating pitted nails in children with a maximum effect seen in 2 months. In order to sustain a continuous therapeutic effect, a bimonthly treatment is suggested.

Child↗

Porphyria cutanea tarda.

Porphyrias are a group of rare metabolic disorders in which excessive quantities of porphyrins, or their precursors, are produced. They are due to specific enzyme deficiencies resulting in abnormalities in the control of the porphyrin-haem metabolic pathway. Porphyria cutanea tarda (PCT) is the most common of all the porphyrias. However this condition is rarely seen in our Asian countries. We describe a patient with PCT who presented clinically with blistering eruptions over the sun-exposed areas. Coral pink fluorescence of uroporphyrins in an acidified urine specimen is diagnostic. Definitive treatment involves the use of low-dose chloroquine and interval venesection.

Biopsy↗

The profile of atopic dermatitis in a tertiary dermatology outpatient clinic in Singapore.

BACKGROUND: Atopic dermatitis is a common, chronic, relapsing, pruritic, eczematous skin condition occurring in patients with a personal or family history of atopy. The aim of this study is to describe the profile of atopic dermatitis seen at a tertiary referral skin center in a tropical multiracial country. METHODS: A retrospective chart review was conducted of all the patients with atopic dermatitis seen during the first six months of 1994. RESULTS: There were 492 patients, age range from 1 month to 74 years, with an equal sex ratio. The prevalence was 2%. The onset of the disease occurred before the age of 10 years in 61.2% of patients. In 13.6% of patients, the onset was after the age of 21 years. Two hundred and fifty four patients (52%) had "pure" atopic dermatitis without concomitant respiratory allergies; 238 patients (48%) suffered from a "mixed" type, with 23% having allergic rhinitis, 12% having asthma, and 13% having both asthma and allergic rhinitis; 231 patients (47%) had at least one first-degree family member with atopy: atopic dermatitis (17%), asthma (15%), and allergic rhinitis (15%). Most of the patients, 416 (84.5%), had subacute dermatitis at presentation. Ichthyosis vulgaris was present in 38 patients (8%) and pityriasis alba in 13 patients (3%). The most common infective complication was bacterial infection (impetiginized dermatitis, folliculitis, cellulitis) present in 95 patients (19%), followed by viral infections (dermatitis herpeticum, viral warts, and molluscum contagiosum) in 17 patients (3%). Allergies were noted in 43 patients (9%). The most common was drug allergy (penicillin and cotrimoxazole) in 28 patients, followed by food allergy in 11 patients. Common aggravating factors reported included heat, sweating, stress, thick clothing, and grass intolerance. Most patients could be controlled with a fairly simple regimen of moisturizers, topical steroids, and antibiotics for acute flares. Short courses of systemic steroids were used in 78 patients (16%). Three patients were treated with phototherapy: two on combined UVA and UVB (UVAB) and one on oral psoralen photochemotherapy (PUVA). CONCLUSIONS: The pattern of atopic dermatitis in Singapore is similar to that reported in the Western literature, except for a lower prevalence and a significant proportion of adult-onset atopic dermatitis.

Adolescent↗

The epidemiology of atopic dermatitis at a tertiary referral skin center in Singapore.

Atopic dermatitis is a common chronic, relapsing, pruritic ecematous skin condition with a predilection for the flexural areas and occurs in patients with a personal or family history of atopy. The aim of this study is to describe the profile of atopic dermatitis seen at the National Skin Centre in Singapore. A retrospective chart review was conducted of all the patients with atopic dermatitis seen during the first six months of 1994. There were 492 patients whose ages ranged from one month to 74 years with an equal sex ratio. The prevalence was 2%. The onset of the disease occurred before the age of 10 years in 61.2% of patients. In 13.6% of the patients, the onset was after the age of 21 years. Two hundred and fifty-four patients (52%) had "pure" atopic dermatitis without concomitant respiratory allergies. Two hundred and thirty-eight patients (48%) suffered from a "mixed" type, with 23% having allergic rhinitis, 12% having asthma and 13% having both asthma and allergic rhinitis. Two hundred and thirty-one patients (47%) had at least one first-degree family member with atropy: atopic dermatitis (17%), asthma (15%) and allergic rhinitis (15%). Most of the patients, 416 (84.5%), had subacute eczema at presentation. Ichthyosis vulgaris was present in 38 patients (8%) and pityriasis alba in 13 patients (3%). The most common infective complication was bacterial infection (impetiginized eczema, folliculitis, cellullitis) present in 95 patients (19%) followed by viral infections (eczema herpeticum, viral warts and molluscum contagiosum) in 17 patients (3%). Allergies were noted in 43 patients (9%) based on the history given. The most common was drug allergies (penicillin and co-trimoxazole) in 28 patients followed by food allergies in 11 patients. Common aggravating factors reported include heat, sweating, stress, thick clothing and grass intolerance. Most patients could be controlled with a fairly simple regimen of moisturizers, topical steroids and antibiotics for acute flares. Short courses of systemic steroids were used in 78 patients (16%). Three patients were treated with phototherapy, Two on UVAB and one on PUVA. The pattern of atopic dermatitis in Singapore is similar to that reported in the Western literature except for a lower prevalence and a significant proportion of adult onset atopic dermatitis.

Adolescent↗

Benign cephalic histiocytosis in Singapore--a review of 8 cases.

AIM OF STUDY: Benign cephalic histiocytosis (BCH) is a rare, benign, self-healing papular eruption that affects mainly children. The aim of this study was to characterise our Singapore children affected by this condition and to review some of the recent literature on non-Langerhans cell histiocytoses. METHODOLOGY: The case records of all cases of BCH seen between January 1990 and December 1996 in our centre were retrieved and analysed. Further details not available in the case records were obtained via a telephone interview with the patients or their parents. RESULTS: A total of 8 cases were seen. There was no sex preponderance or ethnic predilection. The average age of onset was 29 months. All patients began with small brownish papules on the face and sometimes the upper trunk, and most of the lesions regressed in less than 84 months. CONCLUSION: BCH is a benign non-Langerhans cell histiocytosis in which spontaneous resolution is the rule. A small skin punch biopsy is simple, diagnostic and helpful in its management. The management of BCE is expectant and reassurance is sufficient. However the regression and resolution of the lesions may take up to several years.

Age of Onset↗

Cutaneous polyarteritis nodosa: a case report and literature review.

Cutaneous polyarteritis nodosa (CPN) is an uncommon form of vasculitis. It exists as a separate entity, though bearing similar name with polyarteritis nodosa (PAN) which is an aggressive systemic vasculitis with multi-organ involvement. CPN runs a chronic but benign course. Its aetiology is unknown and it usually presents with painful nodules on the legs with mild constitutional symptoms, and extracutaneous features of arthralgias, arthritis, neuropathy and myopathy. No mortality has been reported thus far. It is therefore important to distinguish CPN apart from PAN. Symptomatic treatment with judicial use of systemic steroids and anti-inflammatory agents will suffice in most cases.

Humans↗

Corticosteroid contact hypersensitivity screening in Singapore.

BACKGROUND: Topical corticosteroids have been in use since 1957. Two percent to 5% of patients attending patch test (PT) clinics have problems with corticosteroid contact hypersensitivity. Controversies abound with regard to the choice of steroids in the standard battery, the method of patch testing and reading, and the ideal concentration and vehicle. OBJECTIVE: To assess betamethasone 17-valerate (1% pet.), fluocinolone acetonide (0.25% petrolatum [pet.]), and tixocortol pivalate (1% pet.) used in the authors' standard battery. METHODS: Data were analyzed for patients seen between January 1994 and December 1996 who had positive PT reactions to one or more of these steroids. RESULTS: 3,603 patients had standard PTs, of which 20 had positive reactions to one or more of these steroids. There were three positive reactions to betamethasone 17-valerate, 17 to tixocortol, and none to fluocinolone. On further patch testing to the authors' steroid battery, only one tixocortol-positive patient had a positive reaction to hydrocortisone (1% ethanol/ dimethyl sulfoxide [DMSO]). CONCLUSIONS: Corticosteroid allergy is found to be relatively uncommon in Singapore on the basis of this screening series. The frequency of negative reactions to fluocinolone acetonide is sufficiently low for this corticosteroid to be excluded from the authors standard series. The significance of positive tixocortol reactions remains unknown. From the review of other relevant literature, the authors recommend that budesonide be added to their present series. Testing betamethasone 17-valerate in 1% ethanol may yield more positive allergic reactions. Individuals with a positive allergic PT reaction to one corticosteroid should subsequently be tested to a full corticosteroid series.

Administration, Topical↗