Dermatology — Skin Lesions, Pigment and Hair, NMC MBBS licence examination syllabus (Nepal Medical Council).
A patient rarely arrives saying "I think this is a melanoma". They say a mole has changed — and whether anyone takes that seriously is the whole of the outcome.
The first two dermatology chapters covered rashes: how to describe them, the common ones, and the ones that mean stopping a drug. This chapter covers the single lesion rather than the eruption — the mole that has changed, the patch that has lost its colour, and the hair that is falling out.
Most people have moles, and most moles are harmless. What matters is not the lesion's appearance in isolation but whether it has changed — in size, in shape, or in colour. A lesion that has looked the same for twenty years is reassuring in a way that a new or altering one is not.
The features worth examining for: asymmetry, an irregular border, more than one colour within the lesion, and growth. Bleeding, itching or a lesion that will not heal are worth acting on, but they are late features — waiting for them wastes the advantage that early recognition gives.There is one further observation that costs nothing. A person's moles tend to resemble one another. The lesion that looks unlike all the others on that patient is the one to examine closely, even if no single feature is dramatic.
Basal cell carcinoma is the commonest and the least dangerous. It grows slowly as a pearly nodule, often with a rolled edge and fine vessels across the surface, and may break down into an ulcer. It destroys tissue locally but rarely spreads — which is why it still needs treating, particularly near the eye or nose where local destruction does real harm.
Squamous cell carcinoma is scaly, crusted or ulcerated, often tender, and typically on sun-exposed skin. Unlike a basal cell it can spread. It also arises in scars and long-standing wounds, which gives a practical rule: an ulcer or a scar that has changed, or that will not heal, deserves examination rather than another dressing.
Melanoma is the one that kills. It is pigmented, usually changing, and irregular, and it can spread while still small. Everything in the previous section is aimed at catching it.
A patch of skin that has lost colour has a short differential, and the first step separates the urgent from the cosmetic.
Test the sensation over the patch. A pale patch that has lost sensation is leprosy until proven otherwise, and it needs treating for the patient and for the people around them. Feel the nerve supplying that area for thickening. NMCDE01 covers the disease; the point here is that the test is free, takes seconds, and is the thing most often skipped.Vitiligo gives complete pigment loss with sharply defined edges and entirely normal sensation. It is often symmetrical and often affects the face around the eyes and mouth, and the hands. It carries associations with other autoimmune disease — thyroid disease in particular, covered in NMCMD16 — so it is worth asking about those rather than treating the skin in isolation.
Fungal infection and post-inflammatory change give partial rather than complete loss. A scaly patch on the trunk with slight pallor, or pallor exactly where a previous rash has healed, both fall here.
Hair loss looks like a cosmetic complaint and is often treated as one. The distinction that matters is whether the follicle has survived, because that decides whether anything can grow back.
Non-scarring loss leaves the follicle openings visible on the scalp, and regrowth is possible. Patchy loss with otherwise normal skin, and diffuse shedding a few months after an illness, a fever, childbirth or major stress, both fall here. So does the thinning of iron deficiency and thyroid disease — which is why the useful response is often to look for a cause rather than to treat the scalp.
Scarring loss destroys the follicle. The scalp looks smooth and shiny with no visible follicular openings, and the hair in that area will not return. This is the presentation to refer, because treatment can only protect what has not yet been lost.
A 40-year-old says a mole on his back has grown over six months and now has two colours in it. Change, growth and colour variation together — this needs specialist assessment, not observation. The fact that it does not itch or bleed is not reassurance; those are late features.
A farmer has an ulcer on the lip that has not healed in three months. A non-healing ulcer on sun-exposed skin in someone with heavy sun exposure is a squamous cell carcinoma until shown otherwise. Repeated dressings are the wrong response.
A young woman has a pale patch on her forearm. The first action is to test sensation over it. Loss of sensation makes this leprosy; normal sensation with complete pigment loss and a sharp edge makes vitiligo far likelier — and then it is worth asking about thyroid symptoms.
A woman notices diffuse hair thinning three months after a severe febrile illness. Follicular openings visible, diffuse rather than patchy, with a clear precipitant a few months earlier. This is non-scarring, and the expectation is recovery — but checking iron and thyroid status is reasonable rather than dismissing it.
A mole that is unusual and a mole that has changed. Many people have one odd-looking mole that has been there for decades. Change over months is the finding that matters; unusual-but-stable is much less so.
Basal cell and squamous cell carcinoma. Both are common on sun-exposed skin. The practical difference is that a squamous cell can spread and a basal cell essentially does not — so a scaly, tender, ulcerated lesion warrants more urgency than a slow pearly nodule.
Vitiligo and the pale patch of leprosy. Separated at the bedside by sensation, and by whether pigment loss is complete or partial. This is one of the highest-value examinations in this chapter.
Non-scarring and scarring hair loss. Not decided by how much hair is missing but by whether follicular openings remain.
A changing mole — asymmetry, irregular border, more than one colour, growth. The odd one out among a patient's moles deserves attention.
Melanoma depth at diagnosis drives outcome — which is why early recognition matters more here than almost anywhere in dermatology.
A non-healing ulcer or a changing scar — think squamous cell carcinoma.
A pale patch — test sensation. Anaesthetic means leprosy until proven otherwise.
Hair loss — follicular openings present means possible regrowth; absent means scarring and permanent.
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