The effect of topical tretinoin on photodamaged facial skin: the Thai experience.

Because of the climate in Bangkok, Thailand, a prematurely aged appearance is common in adults beyond 40 years of age. Sixty-one Thai people with moderate to severe signs of dermatoheliosis applied 0.05% tretinoin cream to the face once daily for 6-12 months. Four-mm punch biopsies were obtained from the cheeks before and after treatment. These were formalin-fixed and evaluated histochemically. A surprising degree of photodamage was noted histologically in these dark-skinned people. After 6 months of tretinoin, epidermal atypia and atrophy were largely corrected. There was a great diminution in the density of melanin granules within keratinocytes and corneocytes. Tretinoin did not significantly affect the dermal matrix after 6 months. However, after 12 months, a thin band of new collagen was deposited beneath the epidermis, accompanied by the formation of new vessels (angiogenesis). By global assessment, after 12 months most subjects experienced at least moderate improvement in appearance, especially with regard to hyperpigmented spots and fine wrinkles.

Hendersonula toruloidea infection in Thailand.

Hendersonula toruloidea infection is present in Thailand, where the clinical picture of tinea pedis is scales 61%, erythema 22%, maceration 10.8%, and hyperkeratosis 9%. The diagnosis was confirmed by repeated isolation of H. toruloidea. The slow-growing type was found more often than the fast-growing in the ratio of 2.8:1. In patients with H. toruloidea infection, skin test with Hs antigen of 1:10 was positive. Griseofulvin sensitivity test revealed that the MIC of 20 cultures was more than 100 micrograms/ml. Only 2 out of 93 cases (0.02%) were cured with half-strength Whitfield ointment for 4 months. Pathomechanism of the infection is being studied.

Corynebacterium pyogenes. Its pathogenic mechanism in epidemic leg ulcers in Thailand.

There is a yearly outbreak of endemic leg ulcers in Thailand. Corynebacterium pyogenes, a pathogen to animals, is frequently isolated from the fresh lesions in addition to common pyogenic bacteria such as beta-hemolytic streptococci, mostly group A, and Staphylococcus aureus and Staphylococcus epidermidis. Although circulating titers of IgG and IgM anti-C. pyogenes antibodies were found to be very low in studied cases, intradermal skin test with C. pyogenes vaccine containing nonviable 10(5) microorganisms induced an erythematous reaction with maximum intensity at 6 hours; direct immunofluorescence showed granular deposition of C3 along the dermoepidermal junction at this time. Unexpectedly, the sites of such a skin test that subsequently underwent biopsy presented tender erythematosus induration 1 week later and developed granulomatous ulcerative lesions after 10 days in 11 of 15 patients. Radioimmunoassay for C5a and C5a of arginine demonstrated that C. pyogenes activated complement even in the absence of specific antibodies. These findings suggest that importance of skin injury followed by infection with C. pyogenes in the development of endemic leg ulcers, supporting our hypothesis that the infection of accidentally traumatized skin by C. pyogenes, which is carried by Oriental-eye flies, induces the granulomatous lesions of endemic leg ulcers.

Epidemic leg ulcers in Thailand.

In 1981, two outbreaks of chronic leg ulcers occurred in central Thailand and affected thousands of persons. The lesions were characterized by granulomatous bases with erythematous edges and purulent slough. They were about 1 cm in diameter with irregular shapes. The ulcers lasted two weeks to one month. Ninety percent of the lesions were found on the lower extremities. The outbreak in Nakorn Pathom province occurred in fruit yards. Most of patients were gardeners and students. The outbreak in Ratchaburi province occurred on a sugar cane plantation. The age group of 5-19 years had the highest attack rate in all areas, and there was no significant difference between the attack rates in males and females. The peak incidence occurred in the rainy season with an abrupt decrease at the onset of the dry season. It is hypothesized that trauma precedes the occurrence of the leg ulcer and that a small fly may be a mechanical vector of the causative organism. The organism may be corynebacterium pyogenes, which is a pathogen of certain livestocks and is found in soil. Further studies are planned.

Endemic leg ulcers caused by Corynebacterium pyogenes in Thailand.

Corynebacterium pyogenes was isolated from leg ulcers found in 495 school children during an epidemic in Thailand in 1979 and 1980. Although C. pyogenes is frequently isolated from cattle, sheep, pigs, and goats, and less frequently from rabbits and guinea pigs, it rarely infects humans, where respiratory infections far outweigh skin infections. Cutaneous infections usually begin with a superficial abscess, then a frostbite-like lesion, followed by ulceration and even gangrene.

Subcutaneous chromomycotic abscesses caused by Phialophora gougerotii.

Subcutaneous chromomycotic absesses due to phialophora gougerotii in a 50-year-old woman were characterized by subcutaneous abscesses adhering together through fistulous tracts, rupturing and leaving black crusts over multiple sinuses mimicking mycetoma. Reinfection occurred in contaminated excised lesions. Intradermal inoculation in different anemic patients caused abscesses in 14 days and healed without therapy in eight weeks. No spreading to other organs was found after intraperitoneal inoculation of mice for eight weeks.