Demodicidosis in a child with xantholeukaemia associated with type 1 neurofibromatosis

ARTICLE

Auteur(s) : Mouna BENESSAHRAOUI¹, France PARATTE², Emmanuel PLOUVIER², Philippe HUMBERT ¹, François AUBIN¹

¹ Department of Dermatology  
² Departement of Pediatrics 2 Place Saint Jacques, 25030 Besançon Cedex, France

Article accepted on 17/03/2003

Demodicidosis is a facial dermatosis characterised by erythematous plaques with predominantly follicular papulo-pustules, involving the forehead, the cheeks and the peri-oral area, in which abnormally high numbers of Demodex follicularum are found. Some authors consider this condition as a clinical form of rosacea. It usually affects adult women between the age of 30 and 50, and children are very rarely involved. 
We report the case of a young girl undergoing chemotherapy for chronic myelomonocytic leukaemia (CMML), who developed an unusual facial eruption.

Case report

The 22-month-old girl, Violette V. had been followed for 6 months in the department of Pediatrics for CMML associated with xanthoma and type 1 neurofibromatosis. She was treated by chemotherapy (mercaptopurine, 50 mg daily). A facial eruption was noted (Fig. 1) on one of her monthly visits to the hospital. Physical examination revealed erythematous papules, peri-oral and sub-palpebral pustula with a few lesions on the trunk. Splenomegaly and hepatomegaly were present. She had previously been treated with topical fusidic acid for 10 days with no improvement. The buttocks were not affected and the dosage of plasmatic zinc was normal (12.8 μmol/l; normal values: 11-18 μmol/l). Laboratory values revealed an increased white blood cells count of 120,000/μL with 35,000/μL monocytes, anemia (hemoglobin 9 g/dL) and thrombocytopenia (74,000/μL). A bone marrow biopsy revealed an important monocytic hyperplasia (21.5%), and a slight excess of myeloblastes (10%). Chromosomal analysis was negative for Philadelphia chromosome. Fetal hemoglobin was 20.7% (normal: 0.2-0.8%). A 10% potassium hydroxide preparation revealed the presence of demodex follicularum mites (Fig. 2), but no yeast or fungal elements. Diagnosis of demodicidosis was made in this immunosuppressed patient. Ocular examination was normal. General treatment by metronidazole (250 mg/day) for one month associated with topical formulation containing metronidazole (0.75% gel) was prescribed, leading to the healing of the lesions within 2 weeks.

Discussion

Demodex follicularum and Demodex brevis are permanent ectoparasites of human pilosebaceous follicles. They are rarely found in children and their prevalence increases with aging. Demodex follicularum is found in large numbers in the follicles of the naso-labial folds, nose and eyelids, which are sites with a high concentration of sebaceous glands. This may account for the rare presence of these germs in children who have a low production of sebum.
Demodex follicularum and Demodex brevis have been involved in rosacea, perioral dermatitis and rosacea-like eruptions. However, the pathogenic role of Demodex mites in these conditions remains controversial and it is our opinion that demodicidosis is better considered as a separate entity. Only a few cases of demodicidosis have been diagnosed in children under the age of 5 and most of these cases were associated with leukaemia [1-3] or HIV infection [4], suggesting that immunosuppression could contribute to the proliferation of Demodex, and consequently the onset of demodicidosis. Children with leukaemia treated by chemotherapy develop unusual facial eruptions. Dermatophyte infections, candidiasis, impetigo, folliculitis and acneiform eruptions are well known. Diagnosis of rosacea could have been discussed in our patient, however there were no recurrent facial erythematoses, nor flushes, nor telangiectasia. Perioral dermatitis and zinc deficiency were mentioned because of the localisation of the eruption, but no topical steroid had been applied locally and serum zinc level was normal. Our patient was treated successfully by metronidazole. Some authors [5,6] previously reported the clinical improvement of demodicidosis by metronidazole taken orally or locally, as in the case of our patient. Acaricid treatment by crotamiton or permethrin was sometimes necessary and efficient [1, 7]. Demodicidosis should be added to these various diagnoses in children suffering from immunosuppression caused by malignant tumors, chemotherapy or congenital or acquired immunodeficiency [4]. n

References

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