Skin Examination for Systemic Disease — Viva

Short Case Viva Defence

Examiner instruction

"Please examine this patient's skin. Present your findings and offer a differential diagnosis." [1]

Candidate's model examination and presentation

"Before I begin, I would like to introduce myself, explain the examination to the patient, and obtain consent. I would ensure good natural light and expose the relevant areas while maintaining the patient's dignity." [1]

General inspection: "On general inspection, this young woman has an erythematous rash over both cheeks and the bridge of the nose, with sharp demarcation at the nasolabial folds. The distribution is photosensitive, involving the sun-exposed face. The morphology is macular to slightly raised erythema. There is no blistering, no purpura, and no scale." [1]

Hands: "In the hands, the nails are normal. There is no clubbing, no koilonychia, no Beau lines, and no splinter haemorrhages. The nail-fold capillaries are normal — fine, evenly spaced, hairpin loops with no dilation, no tortuosity and no dropout on close inspection. There are no Gottron papules over the metacarpophalangeal or interphalangeal joints. The palms are normal with no palmar erythema. The fingers show no sclerodactyly, no calcinosis, and no telangiectasia." [1]

Face: "On examination of the face, the rash is a flat, erythematous, confluent eruption over both cheeks and the bridge of the nose, with sharp sparing of the nasolabial folds. There are small, painless ulcers on the hard palate. There is no heliotrope rash — the upper eyelids are a normal skin colour. There is no periorbital oedema, no xanthelasma, and no arcus senilis. There are two spider naevi on the anterior neck, each with a central arteriole and radiating vessels, blanching on pressure. There is no moon face and no plethora." [1]

Trunk: "On the trunk, there is no acanthosis nigricans in the axillae, the back of the neck, or the inguinal folds. There are no striae. There is no gynaecomastia. There are no cafe-au-lait macules and no shagreen patches. There is no caput medusae." [1]

Legs: "On the legs, there are no tender, erythematous, subcutaneous nodules on the anterior shins (no erythema nodosum). There are no ulcers (no pyoderma gangrenosum). There are no yellow-brown atrophic plaques (no necrobiosis lipoidica). There is no pretibial myxoedema. There is no purpura — palpable or non-palpable. There is no livedo reticularis or racemosa. There are no digital infarcts." [1]

Mucosae and scalp: "The oral mucosa shows the painless ulcers on the hard palate. There is no conjunctival injection. The scalp shows no scarring alopecia or discoid lesions." [1]

Summary: "In summary, this patient has a photosensitive malar rash sparing the nasolabial folds, with painless oral ulcers on the hard palate, and two spider naevi. The findings are consistent with systemic lupus erythematosus. I would like to take a full history including the sun exposure, the joint symptoms, the drug history, and a family history of autoimmune disease, and I would check the full blood count, the renal and liver function, the urinalysis, the antinuclear antibodies, the extractable nuclear antigens including anti-dsDNA and anti-Smith, and the complement levels [1]."

Examiner probing questions and model answers

Q1: "You described the malar rash as sparing the nasolabial folds. Why is this the case, and what is the main differential?" [1]

"The malar rash of SLE is a photosensitive reaction to ultraviolet light, and the nasolabial folds are physically shielded from sunlight by the overlying tissue, so the sparing is a structural consequence of the photosensitivity mechanism. The main differential is rosacea. Rosacea involves the nasolabial folds — it does not spare them — because it is a chronic inflammatory disorder of the pilosebaceous unit rather than a photosensitive reaction. Rosacea also has papules and pustules, and is associated with flushing, telangiectasia, and rhinophyma. The other facial rash to distinguish is the dermatomyositis rash, which is more violaceous (ilac-coloured), is accompanied by the heliotrope rash on the upper eyelids and the Gottron papules on the knuckles, and may involve the scalp and the shawl area. The laboratory confirmation is the ANA, the anti-dsDNA, and the anti-Smith for SLE, and the creatine kinase and the myositis-specific antibodies for dermatomyositis [1]."

Q2: "How do you examine the nail-fold capillaries, and what do the changes mean?" [1]

"I examine the nail-fold capillaries by placing a drop of immersion oil on the proximal nail fold and using a dermatoscope or an ophthalmoscope set at 10 to 20 diopters as a magnifier, held close to the nail fold. I am looking for the pattern and the morphology of the capillary loops. Normal nail-fold capillaries are fine, evenly spaced, hairpin-shaped loops with no dilation and no dropout. In systemic sclerosis and dermatomyositis, the capillaries become dilated and tortuous, with giant capillaries and microhaemorrhages, and the loss of capillaries produces the avascular areas called dropout. These changes reflect the microvascular damage from the autoimmune process, and they are a sensitive and specific bedside sign of the active connective tissue disease. The presence of the capillary changes, with the periungual erythema and the ragged, hypertrophic cuticles (the Samitz sign), supports the diagnosis of dermatomyositis [3]."

Q3: "What is the significance of the spider naevi, and how do you distinguish them from other vascular lesions?" [1]

"Spider naevi, or spider telangiectasia, are a central arteriole with radiating fine vessels, found in the distribution of the superior vena cava — above the nipple line, on the face, the neck, the upper chest, and the arms. They blanch on pressure (the central arteriole is the feeder vessel) and refill from the centre outward. More than three to five spider naevi, in a man or a non-pregnant woman, suggests chronic liver disease (cirrhosis) with the oestrogen excess from the impaired hepatic metabolism. Spider naevi also occur in pregnancy, where they are a benign, oestrogen-driven phenomenon. I distinguish them from the simple telangiectasia of rosacea or chronic sun damage (which do not have the central arteriole and the radiating pattern), and from the petechiae (which do not blanch, because the blood is extravascular). The finding of two spider naevi on this patient, with the malar rash and the oral ulcers, does not by itself make the diagnosis of cirrhosis — the number is within the normal range — but I would check the liver function as part of the SLE workup, because SLE can involve the liver and because the autoimmune liver diseases (primary biliary cholangitis, autoimmune hepatitis) can coexist with SLE." [1]

Q4: "If this patient also had palpable purpura on the lower legs, what would that signify, and how would it change your investigation approach?" [1]

"Palpable purpura would signify small-vessel (leucocytoclastic) vasculitis — the immune complex deposition in the postcapillary venules produces the inflammation and the red cell extravasation that make the lesion raised and non-blanching. In a patient with SLE, palpable purpura would suggest lupus vasculitis, which can involve the skin, the kidneys (lupus nephritis), the gastrointestinal tract (mesenteric vasculitis), and the nervous system. My investigation approach would expand to include the ANCA (to exclude the overlap with the ANCA-associated vasculitides), the cryoglobulins and the complement (for the cryoglobulinaemic vasculitis), the hepatitis B and C serology (because the hepatitis C with the mixed cryoglobulinaemia can mimic lupus), the skin biopsy with the direct immunofluorescence (which shows the leucocytoclastic vasculitis and, in lupus, the immune complex deposition at the dermoepidermal junction), and a careful assessment of the renal function with the urinalysis and the urine microscopy for the red cell casts [1]."

Q5: "How do you distinguish erythema nodosum from the other pretibial dermatoses?" [1]

"The four pretibial dermatoses to distinguish are erythema nodosum, pyoderma gangrenosum, necrobiosis lipoidica, and pretibial myxoedema. Erythema nodosum presents as bilateral, symmetric, tender, erythematous, subcutaneous nodules on the anterior shins — the lesions are deep in the panniculus and do not ulcerate. Pyoderma gangrenosum presents as a painful, rapidly enlarging ulcer with an undermined, violaceous, boggy border, often preceded by a pustule, and characterised by pathergy. Necrobiosis lipoidica presents as bilateral, symmetric, yellow-brown, atrophic plaques with a waxy surface and telangiectatic borders — the yellow colour is from the lipid deposition, and the atrophy is from the collagen degeneration. Pretibial myxoedema presents as bilateral, symmetric, firm, non-pitting, waxy plaques with a peau d'orange surface, in the context of Graves disease. The discriminating features are the morphology (nodules versus ulcer versus plaque), the colour (erythematous versus violaceous versus yellow-brown versus waxy), the surface (normal versus undermined versus atrophic versus peau d'orange), and the associated systemic disease (sarcoid and IBD for erythema nodosum, IBD for pyoderma gangrenosum, diabetes for necrobiosis lipoidica, Graves for pretibial myxoedema) [5][6][7]."

Q6: "You mentioned acanthosis nigricans in your trunk examination. When would you be concerned about malignancy?" [1]

"I would be concerned about malignant acanthosis nigricans when the condition is rapidly progressive, extensive, or involves unusual sites such as the oral mucosa or the palms — the so-called tripe palms. I would also be concerned when the acanthosis nigricans occurs in a non-obese patient without the metabolic risk factors of insulin resistance, type 2 diabetes, or obesity, or when it is accompanied by an unexplained weight loss. Malignant acanthosis nigricans is a paraneoplastic phenomenon, most commonly associated with an intra-abdominal adenocarcinoma — the stomach is the classic primary, but the pancreas, the colon, the liver, and the ovary are also reported. The mechanism is thought to involve the tumour-derived growth factors (the transforming growth factor alpha and the insulin-like growth factors) stimulating the keratinocyte and the fibroblast proliferation. When I suspect the malignant variant, I perform an urgent upper gastrointestinal endoscopy and a CT of the chest, the abdomen and the pelvis. The benign acanthosis nigricans of insulin resistance, by contrast, is chronic, progressive, confined to the flexures, and occurs in the context of the metabolic syndrome [8]."