Histological analysis of pigmented skin abnormalities (PSA). A: Serial sections of PSA were either directly HE stained (a-c) or bleached in a benzylalcohol/aceton/H2O2 based bleaching solution before HE-staining was performed (d-f). Yellow arrows point to the pigmented and to the bleached areas respectively within the cyst lumen; green arrows point to pigmented and bleached melanocytes respectively. B: Immunofluorescence of epidermoid cysts. HDGF was detected by incubation with anti-mouse HDGF antibody and Cy3-conjugated goat-anti-rabbit antibody (a-f). Nuclei were stained with DAPI. a-c HDGF; d-f merge of HDGF, DAPI and transmitted light. Green arrows point to HDGF-positive nuclei in pigmented areas. Scale bars equate 100 μm.