Skin Analysis, Skin Types, and Skin Disorders and Diseases
Typing and analysis
Fitzpatrick I–VI describes how skin responds to sun and predicts burning and pigmentation risk. Descriptive types - normal, dry (alipidic), oily, combination, sensitive - are what drive product choice. Analyze clean skin under good light with magnification, and palpation for oiliness and texture. A Wood's lamp can help you see oil (yellow), dehydration (violet), and pigmentation (brown).
Lesions: primary versus secondary
Primary lesions appear first: macule, papule, pustule, vesicle, bulla, wheal, nodule, cyst, tumor, plaque. Secondary lesions are changes to existing lesions: scale, crust, fissure, excoriation, scar, keloid, ulcer. Learn the pairs - a papule is a small solid bump with no fluid; a pustule contains pus; a wheal is an edematous response such as a hive or insect bite.
Disorder versus disease, and your scope
A disorder is an abnormality; a disease has recognizable symptoms and progression. You may treat cosmetically, but you never diagnose. Do not treat conjunctivitis, impetigo, herpes simplex, tinea, lice, scabies, open or weeping lesions, or an undiagnosed rash - refer out. Skin cancer warning signs follow ABCDE: asymmetry, border irregularity, color variation, diameter, evolving.
Pigmentary concerns (melasma, post-inflammatory hyperpigmentation) need gentle care, sun protection, and realistic expectations; aggressive exfoliation can worsen them.
Traps: calling a fissure or excoriation primary; calling a wheal secondary; believing you can identify a disease in order to treat it. A comedone is a follicle impaction, not one of the classic primary lesions.
Rule of thumb: if a question presents a rash or lesion you cannot confidently name, the correct answer is 'do not treat; refer to a physician.'