Pigmentation of open comedones. An ultrastructural study

Ultrastructural examination of expressed "black" open comedones did not disclose any single melanosomes or melanosome complexes. If there is any melanin present in comedonal plugs, the amount is minimal, and it cannot be the source of the black color.     

Generalized granuloma annulare with open comedones in photoexposed areas

Granuloma annulare (GA) is a noninfectious necrobiotic granuloma, which can present as localized or generalized patterns. We present a case of generalized GA with multiple large open comedones over the lesions in a woman with hypothyroidism and diabetes mellitus. GA is associated with collagen and elastic-fibre damage, which may lead to loss of follicular support and resultant open comedone formation, analogous to solar elastosis or senile comedones. The rapid recovery of our patient after treatment with of oral hypoglycaemics supports the role of insulin resistance as a predisposing factor for GA.     

Ultrastructural changes in open comedones following treatment of cystic acne with isotretinoin

The primary change found in cellular material expressed from open comedones of patients who had been treated with isotretinoin was disintegration of desmosomes. Consequently, there was lack of cohesion between cornified cells. A marked decrease in the quantity of sebaceous material and bacteria was also evident within the comedones.     

Bacterial flora of comedones

Open comedones from thirty-eight patients with acne vulgaris on the face or back were compared for microbial flora. A total of eighty-three comedones from the face and sixty-three from the upper back were individually processed for quantitative bacterial analysis. The greatest difference between the flora of comedones at these two sites was that 44.6% of comedones from the back (compared to 9.6% from the face) harboured no aerobic cocci. The decreased prevalence of staphylococci in the lesions from the back reflects the relative absence of these organisms in isolated follicles from normal uninvolved skin of the back. The geometric mean count of anaerobes in comedones from the back was in the same range as the count found in isolated follicles in normal uninvolved skin in a previous study. This work supports the concept that the bacterial flora of comedones is an extension of the follicular flora and may be unrelated to the event of comedogenesis.     

Familial dyskeratotic comedones

Familial dyskeratotic comedones (FDC) is a rare autosomal dominant inherited condition, characterized by widespread, symmetrically scattered, comedone-like, hyperkeratotic papules, which are cosmetically unappealing. These lesions appear around puberty and show a predilection to involve the trunk, arms and face. The lesions are asymptomatic and gradually worsen with time. Histology shows invagination of the epidermis with a lamellar keratinous plug and focal evidence of dyskeratosis. This condition is generally refractory to therapy. We report here two cases with this rare disorder who had a strong familial history of the same disorder.     

Familial dyskeratotic comedones

Familial dyskeratotic comedones (FDC), an autosomal dominant condition, was first described by Carneiro, Dickson & Knox (1972) in four members of one family. A further case, with a brother similarly affected, is described here.     

Familial dyskeratotic comedones

We report a 49-year-old white woman having asymptomatic hyperkeratotic comedone-like lesions on her legs, arms and trunk. Her sister is similarly affected, but less severely. The clinical and histopathological features indicated a diagnosis of familial dyskeratotic comedones, a rare autosomal dominant condition.     

Disseminated congenital comedones

A 3-month-old boy with congenital and extensive skin comedones without any other extracutaneous manifestations is reported. This patient does not fit with other reported disorders of congenital or childhood extensive comedones, such as nevus comedonicus, familial dyskeratotic comedones, idiopathic disseminated comedones, childhood flexural comedones, and acne neonatorum.     

Penetration of topical clindamycin into comedones

Comedones were removed from patients on topical clindamycin and assayed for that antibiotic by of two methods. Prominent levels were found in eight of ten patients by one bioassay method. Once whole comedones from a patient were found to be positive, other comedones were microdissected to separate the external and internal portions. Prominent levels of clindamycin were found in the inner portion as early as 2 weeks. Further, the antibiotic could always be found in the internal portion when it was present in the external layers. Using the more sensitive of two bioassay methods, the whole comedonal level of clindamycin ranged from 0 to 5 microgram/mg of comedonal material, with an average level of 0.824 microgram/mg. The significance of this is discussed.