All of the following are correct in the initial acute stage of management, except:
a. Cessation of all antihypertensive medications.
b. Full lead ECG and continuous rhythm monitoring.
c. Dextrose insulin infusion, oral polystyrene, sulphonate resins and bicarbonate.
d. Rehydration with normal saline.
e. Urgent ultrasound of the kidneys.
f. Urgent MR angiography of the renal arteries.

F. The underlying diagnosis is bilateral atherosclerotic renal artery stenoses. Clues to the diagnosis include new onset hypertension in this patient, with a background of severe coronary artery disease and refractory hypertension. The disease has two important clinical presentations: renovascular hypertension and ischemic nephropathy. Some patients may present with “flash” pulmonary edema with poorly controlled blood pressure despite normal left ventricular function and acute renal failure upon starting an ACE inhibitor.

His presentation of acute renal impairment is multifactorial — dehydration (causing his acute weight loss) and relative hypotension after acute gastroenteritis leading to further renal ischemia. An ACE inhibitor will further aggravate the problem, since both kidneys distal to the high grade stenoses, require high levels of angiotensin II to maintain adequate perfusion. With an ACE inhibitor, renal perfusion in both kidneys is markedly diminished.

Acute management of this patient is quite straightforward and is mainly targeted towards lowering his serum potassium, monitoring the cardiac rhythm, rehydration and cessation of all antihypertensive medications, particularly the ACE inhibitor, to prevent further renal ischemia.

Obstructive uropathy remains an important differential diagnosis in patients with acute renal impairment, which can be easily ruled out by renal ultrasound. Bilateral renal artery stenoses may not produce asymmetric kidney size unless one renal artery is affected out of proportion to the other. MRA is a powerful way to screen for renal artery stenosis. However it should not be the first investigation to arrange in the acute phase, due to acute renal impairment. An acute renal failure can occur after exposure to gadolinium-based contrast agents in patients with moderate to severe chronic renal failure. There are recent reports in which exposure to gadolinium compounds has been linked to the development of nephrogenic systemic fibrosis in this patient population, which is a cause for concern. It is of great importance that radiologists be aware of this serious disease and exercise caution when considering the use of gadolinium-based contrast media in patients with moderate (glomerular filtration rate, <60 mL/min/1.73 m2) to severe (glomerular filtration rate, <15 mL/min/1.73 m2) renal disease. Therefore this test was only ordered after improvement of his renal function test. Bilateral renal artery stenting will be the treatment of choice in this patient.

What is the most likely diagnosis and what are the differential diagnoses?

The clinical diagnosis is oral lichen planus (LP). The differential diagnoses are leukoplakia, discoid lupus erythematosus and, oral candidiasis.

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What is the aetiology and what are the possible associating factors?

The etiology of LP is unknown and the possible associating factors include autoimmune diseases, hepatitis C infection, metallic dental restorative materials such as amalgam and gold. Medications such as thiazide diuretics, beta-blockers, non-steroidal anti-inflammatory drugs, gold, penicillamine, antimalarials, quinidine and angiotensinconverting enzyme inhibitors may also cause lichenoid eruption of the skin but usually the with mucosa is spared.

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How many clinical types of this disease are there that you know of?

Clinical types of oral LP such as reticular (usually asymptomatic), atrophic, erosive or ulcerative (usually painful) and bullous types have been described.

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What are the available treatments?

Keeping good oral hygiene can reduce the symptoms and help prevent infection. Physical injury to the mouth should be avoided because this can lead to new eruptions (Koebner phenomenon). The patient should stop smoking because tobacco smoking may increase the risk of squamous cell carcinoma. Topical steroids in dental paste or inhalant powder, intralesional steroids or cyclosporine mouthwash can be used for the symptomatic or severely symptomatic oral LP.

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What would be the course of disease?

Unlike cutaneous LP, oral LP usually persists for decades. Since there is a slight increase in incidence of oral cancer (squamous cell carcinoma) in patients with oral LP, patients should be followed up regularly.

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