Bimatoprost-induced periocular skin hyperpigmentation: histopathological study.
OBJECTIVE
To investigate light microscopic and ultrastructural changes in bimatoprost-induced skin hyperpigmentation.


METHODS
Eyelid biopsy specimens from bimatoprost-treated patients and matched controls were examined by light microscopy and transmission electron microscopy. Using an image analyzer, melanin granules were counted on Fontana-Masson-stained sections, and melanosomes were counted on electron micrographs. Immunohistochemical analysis was performed with antibodies against S100 and CD3. Positively labeled cells were counted.


RESULTS
By light microscopy, a marked increase in the number of melanin granules was noted in the bimatoprost-treated specimens. Electron microscopy demonstrated dermal melanocytes with prominent rough endoplasmic reticulum and abundant normal-sized melanosomes in different stages of maturation as compared with control specimens. Furthermore, the keratinocytes of the bimatoprost-treated specimens showed abundant mature melanosomes when compared with controls. Also of note, atypical melanocytes were absent in both specimens. The S100-positive melanocytes were comparable in bimatoprost-treated and control specimens. Few CD3- and CD68-positive cells in the bimatoprost-treated specimens were noted in both groups.


CONCLUSIONS
Bimatoprost-induced periocular hyperpigmentation is caused by increased melanogenesis. There was no evidence of melanocyte proliferation or prostaglandin-induced inflammation in the specimens that were examined.
Kapur
Rashmi
R
Department of Ophthalmology and Visual Sciences, University of Illinois, Chicago 60612, USA.
Osmanovic
Smajo
S
Toyran
Sami
S
Edward
Deepak P
DP
D000368:Aged; D000577:Amides; D000959:Antihypertensive Agents / Q000009:adverse effects*; D000069580:Bimatoprost; D001706:Biopsy; D017252:CD3 Complex / Q000378:metabolism; D003008:Cloprostenol / Q000031:analogs & derivatives; D005141:Eyelid Diseases / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000188:drug therapy; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects; D015603:Keratinocytes / Q000648:ultrastructure; D008055:Lipids / Q000009:adverse effects*; D008548:Melanosis / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology*; D020460:Melanosomes / Q000378:metabolism / Q000648:ultrastructure*; D008875:Middle Aged; D009418:S100 Proteins / Q000378:metabolism
D000577:Amides; D000959:Antihypertensive Agents; D017252:CD3 Complex; D008055:Lipids; D009418:S100 Proteins; D003008:Cloprostenol; D000069580:Bimatoprost