Demodicidosis simulating acute graft-versus-host disease after allogeneic stem cell transplantation in one patient with acute lymphoblastic leukemia

Demodex Folliculitis of the Scalp: Clinicopathological Study of an Uncommon Entity

Demodex is a saprophytic mite in humans commonly present in the pilosebaceous units, which has been implicated as a pathogen in several skin conditions. The clinical presentation and histopathology of Demodex folliculitis of the scalp have been described in only a few case reports. This study was performed to further elucidate the clinicopathological features of this entity. We have studied 333 consecutively submitted scalp biopsies performed for hair loss and alopecia. All specimens were completely step-sectioned. Biopsies with Demodex mites were further studied histopathologically, and the patients' clinical files were reviewed. There were 17 biopsies (5.1%) with Demodex in at least 1 pilosebaceous unit. Based on the clinical presentation, histopathology, and response to therapy, Demodex was considered to be nonpathogenic in 13 cases. The remaining 4 cases were characterized by hair loss, scalp erythema, scales, and pustules. There were 2 or more pilosebaceous units with Demodex along mononuclear and/or neutrophilic infiltrates around and in the involved follicles and occasionally granulomas. All 4 cases responded completely to metronidazole therapy. In conclusion, Demodex is infrequently found in scalp biopsies for hair loss and alopecia, and, in most cases, it does not seem to be pathogenic. Occasionally, however, it is associated with folliculitis characterized by hair loss, erythema, scales, and pustules clinically; neutrophilic and/or mononuclear-cell folliculitis with occasional granulomas histopathologically; and a prompt response to anti-Demodex therapy.

Assessment of demodex presence in acne-like rash associated with cetuximab

CONTEXT

Cetuximab is an epidermal growth factor receptor inhibitor. It is frequently used in the treatment of solid tumors. However, it has a high potential to cause acne-like rash. Demodex mites, which are known to increase in number in immunosuppressive circumstances, are closely related to the acneiform lesions.

OBJECTIVE

The aim of this study is to evaluate the presence of demodex mites in acne-like rash that appears under the treatment of Cetuximab.

METHODS

We reviewed the medical records of patients who applied to our clinic with cetuximab induced papulopustular rashes between November 2014 and March 2016. Demodex sampling was performed by standardized skin surface biopsy (SSSB) in a total of 11 patients (eight males and three females). Infestation was defined as at least 5 living parasites/cm² of skin.

RESULTS

Upon the SSSB examination in 10 out of the 11 patients, no demodex mites were detected. Demodex mites were found in only one of the patients. This patient, in whom two dead Demodex folliculorums were found through facial sampling, was also regarded as negative since his demodex density was under the threshold limit value.

CONCLUSION

In this study, it has been concluded that acne-like rash that develops under the treatment of cetuximab is not related to the presence of demodex mites. Papulopustular eruptions that develop under cetuximab treatment should not be directly correlated with the presence of demodex; first SSSB and demodex presence should be evaluated.

Demodex mites

Demodex mites are normal inhabitants of human hair follicles. D folliculorum is found predominantly in the follicular infundibulum of facial skin and is typically present in small groups. D brevis, the smaller of the two species, predominates on the trunk, typically as solitarily mites within the sebaceous glands and ducts. In a wide variety of animals, Demodex mites are recognized as a cause of mange. The role of Demodex mites as agents of human disease has been more controversial, but evidence favors their involvement in acneiform eruptions, folliculitis, and a range of eruptions in immunosuppressed patients.

Demodex mite infestation of unknown significance in a patient with rhinocerebral mucormycosis due to Apophysomyces elegans species complex

Demodex mites have been reported in the past as a cause of facial rash in immunosuppressed patients. Here, we report an interesting case of possible demodicosis associated with rhinocerebral mucormycosis. The association of mites with a fungus was detected on direct microscopic examination of the scrapings of a nasal ulcer. The mite and the fungus were identified as Demodex folliculorum and Apophysomyces elegans species complex, respectively.