Histology melanocytes

We have seen that phenol has a marked effect on dyschromias, and it incapacitates melanocytes, even if it does not destroy them histologically (Figure 30.9). Even if many melanocytes are still physically present in the basal layer, they can no longer produce melanin (partially or completely). 

Histologically, freckles are characterized by a normal number of melanocytes in the basal layer. The melanocytes are, however, larger and more dendritic , and give up their melanosomes more readily to the keratinocytes. Freckles disappear completely and definitively with phenol. A TCA peel to the papillary dermis will also get rid of freckles. A local phenol peel is contraindicated on light skin phototypes - which in principle are a good indication for phenol - with freckles, as they will disappear where the phenol has been applied and will persist in the surrounding areas. A combination of local Lip Eyelid and Unideep (TCA to the papillary dermis) is suitable to avoid this freckle demarcation Hne. 

Histological sections taken after phenol peels show that melanocytes are still present, though many of them are inactive. Clinically, fewer melanocytes are rendered inactive with the latest formulas (e.g. Lip EyeHd ). This means that long-term prognosis for sun exposure can be better with these peels than with older phenol formulations and that a few months or even a year after the peel, it is often difficult to see a demarcation Hne. The melanocyte toxicity of phenol means the practitioner must choose the product most suited to the patient s complexion. 

A 73-year-old man presented with a dark coloured patchy macular pigmentation on the nasal columella. The patient had no personal or family history of skin cancer and was himself not aware of the lesion. His medical history consisted of asthma, peripheral vascular disease, hypertension and nocturnal leg cramps and had been on simvastatin, bendroflumethiazide, quinine, salbutamol and aspirin for several years. Histology of biopsy tissue showed evidence of sun-damaged skin with increased basal melanin pigmentation and pigment incontinence in the superficial dermis. There was no evidence of increased melanocyte numbers, dysplasia... 

---