What is Hypo-depigmented lesion seen in : and explain in detail?
B i.e. Naevus depigmentosa Freckles (or ephelides), Melasma (chloasma or mask of pregnancy), Mongolian spots, Cafe au lait, Becker's nevus or melanosis (pigmented hairy epidermal nevus), nevus of Ota and nevus of Ito cause hyperpigmented patches (Mn: "Free Meal & Mongolian Cafe BOY = BOI arer hyperpigmented"). Whereas, Nevus depigmentosus (or achromicus), nevus anaemicus, Sutton's (Halo) nevus (leukoderma acquisitum centrifugum), hypomelanosis of Ito and Piebaldism leads to hypopigmentation. (Mn- "Pie DASH nevus are hypopigmented"). Becker's nevus is sporadically acquired disorder (may be of familial occurance), 5 times more commonly affecting males. It is usually first noticed during adolescence, initially pale in colour which becomes more prominent during sun exposure. It follows Blaschko's lines, but with lack of conformity (d/t late occurance). It stas as an area of irregular macular (hyper) pigmentation with geographical outline usually on shoulder, anterior chest or scapular region. Once present it remains indefinitely and shows predisposition to androgen sensitivity (since it is prone to acne & hyperichosis). Lesion may show central thickening and increased terminal hairs on & around the lesion. Becker's nevus syndrome is Becker's nevus with ipsilateral non cutaneous developmental abnormalities like breast hypoplasia, supernumerary nipples, spina bifida etc. Nevus of Ota (oculo-dermal melanocytosis/nevus fuscocaeruleus ophthalmo-maxillaris) is usually congenital & unilateral slate brown or blue hyperpigmentation in the areas of skin, sclera, cornea, iris, retina, ocular muscles, orbit & hard palate supplied by ophthalmic and maxillary division of trigeminal nerve, more prevalentally in Japanese. Nevus of Ito is hyperpigmentation in area supplied by posterior supraclavicular and lateral brachial cutaneous nerves, commonly in Japanese.