A great professional article on wen trimming:
The area in purple is the wen which is composed of hyperplasia of epidermis and increased number of mucous cells" The dark area is melanin bordering the "increased deposition of adipose tissue in the subcutaneous layer" but the wen itself is not adipose or fat but rather hyperplastic (over grown and expanded) epidermis and mucous cells. The epidermis is the skin on top of and into which scales are embedded.
