Progressive macular hypomelanosis pathogenesis and treatment: a randomized clinical trial

Strains of the Propionibacterium acnes type III lineage are associated with the skin condition progressive macular hypomelanosis

“…Furthermore, the observation that type III strains recovered from PMH lesions could not be identified as P. acnes using the current Rapid ID 32A multi-test identification system, unlike strains of types I and II, is also consistent with the results previously described for AFLP DNA group 3 strains isolated from PMH patients 3 . While the high rate of P. acnes recovery, especially type III, from PMH lesions does not in itself prove causality, the circumstantial evidence linking this bacterium to the aetiology of the condition is strong, especially the low rate of recovery of P. acnes form peri-lesional skin and the resolution of symptoms (repigmentation) with anti-bacterial therapeutics 5 6 7 8 . Other factors are, however, also likely to be important in the development of PMH including genetic factors, hormonal influences and the host response to the skin microbiota, which may prevent disease in some individuals but not in others.…”

“…Furthermore, analysis of lesions under a Wood’s lamp reveals a red follicular fluorescence due to the production of porphyrins by the bacterium, a phenomenon not observed with healthy pigmented skin on the trunk region24. Consistent with a role for P. acnes in PMH, the administration of topical and oral antibacterials and UVA phototherapy often proves an effective treatment leading to repigmentation of the lesions5678.…”

“…While the underlying cause of this condition remains unclear, there is growing evidence to suggest that the Gram-positive anaerobic skin bacterium Propionibacterium acnes may play an important role in the aetiology of the condition 2 3 4 . In particular, P. acnes is frequently cultivated from lesional biopsies and has been observed in histological sections, but recovery from peri-lesional, normal-looking skin is infrequent 5 . Counts of the bacterium in lesional skin are also much higher as measured by quantitative real-time PCR (qPCR) 4 .…”

IsCutibacterium(previouslyPropionibacterium)acnesa potential pathogenic factor in the aetiology of the skin disease progressive macular hypomelanosis?

“…Histologically, PMH does not appear to be associated with any significant abnormalities of the dermis apart from a decrease in epidermal pigment, but a mild perifollicular infiltrate of lymphocytes has been observed in some, but by no means all, lesional skin samples. 2,4,[6][7][8][9][10] Detailed ultrastructural studies have provided evidence that PMH results from altered melanogenesis, leading to reduced pigmentation, and changes in melanosome size, aggregation, maturation and distribution. 2,3,6,[8][9][11][12] Furthermore, it does not appear that defects in melanosome degradation play a role in the pathophysiology of PMH as there is no evidence for disintegrated melanosomes in the lysosomal compartments of PMH lesions.…”

“…The presence of C. acnes within hypopigmented lesions from patients with PMH, but not normal pigmented skin from the trunk of the same patient, can also be observed upon Gramstaining, revealing Gram-positive rods with a high population density. 1,4,9 Furthermore, upon examination of the skin in a 29 dark room with UV radiation from a Wood's lamp, a punctiform orange-red follicular fluorescence within hypopigmented spots is observed due to the presence of porphyrins produced by the bacterium, such as coproporphyrin III; this fluorescence is absent in peri-lesional normal skin. 1,4,7,10,12 Interestingly, while this characteristic florescence of PMH lesions upon Wood's lamp examination has been described in many studies, it has not been observed in all (see section "PMH in the apparent absence of lesional C. acnes").…”