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manifestations of diabetes , there are many other non-infectious dermatological manifestations which are important for clinicians to assess in patients with longstanding diabetes . These include skin tags , carotenaemia ( yellow
skin and nails ), diabetic dermopathy ( skin spots ), rubeosis faciei ( flushed face and neck ) and foot ulcers . 1
Outcome
Three months later , Geoff ’ s fasting glucose reduces to 6.5mmol / L ( normal 3-5.4 ) and HbA1c to 7 % ( normal < 6.5 %, target < 7 %). The acanthosis nigricans remains but is not
troubling him . Although metformin may improve insulin resistance , Geoff ’ s mild to moderate renal impairment tips the balance towards risk associated with resuming this medication . In discussion with Geoff
The underlying pathophysiology driving the proliferation of keratinocytes and dermal fibroblasts in acanthosis nigricans is not fully understood .
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and his family , a decision is made not to further increase his insulin with a view to treating the acanthosis nigricans specifically , given the lack of response to up-titration to date , his advanced age , the lack of concern with the acanthosis itself and risk of hypoglycaemia with escalated insulin dosing .
References on request from kate . kelso @ adg . com . au
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Figure 1 . There is a dry , pigmented rash in both axillae , with no associated scale , tenderness or discharge .
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ANSWER The answer is c . Nail psoriasis is an autoimmune condition that is usually associated with and preceded by cutaneous plaque psoriasis . It is characterised by changes in the fingernails and toenails whereby the nail plate , nail bed and matrix , and skin around the nail have signs of dystrophy and surrounding erythematous plaques . 1
Up to 80 % of patients with psoriasis on other areas will also have nail involvement , 2 and this is associated with a greater severity of whole-body psoriasis . 3 This patient presented with well demarcated psoriatic lesions on the body and scalp as well as toenail involvement .
Mild cases can be treated with topical corticosteroids . A trial of ultraviolet B ( UVB ) therapy is another option . This approach can slow the growth of skin cells , improving psoriatic lesions . In severe cases , biologics may be indicated to improve skin and nail lesions . 1
Differential diagnoses include trauma to the nail ; however , this patient denied any trauma incidents related to the fingernails .
Fungal pathologies present as onychomycosis , with discolouration and crumbling of the nail . While this can easily be confused with nail psoriasis , a telltale feature of psoriatic causes is the ‘ oil drop ’ sign , referring to a small salmon-coloured patch on the nail . 4 To rule out fungal involvement on the nail , a clipping of the nail should be taken and sent for mycological microscopy and culture .
Nail lichen planus is a chronic inflammatory condition that can also cause nail dystrophy and onychorrhexis . This too is associated with skin lesions ; however , unlike psoriasis , they are less scaly . A nail biopsy is performed to confirm diagnosis .
References on request from kate . kelso @ adg . com . au
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