The skin ’ s the thing

Poor diabetes control is suspected to be the cause of this patient ’ s dermatological disturbance , but the GP believes the mechanism might not be infectious .

Rohit Govindarajan Senior medical student , Curtin Medical School , Curtin University , Perth , WA .

Dr Dan Xu Academic co-ordinator , general practice research and international collaboration , Curtin Medical School , Curtin University , Perth , WA .

GEOFF , a 79-year-old retiree , is a long-term aged care resident . The nursing staff report that he has had a red rash in both axillae for the past four months . Although this is not bothering Geoff , he wonders why it is lingering , despite treatment with a potent topical anti-inflammatory .

On examination , he appears well with vital signs within normal limits . On closer inspection of both axillae , there is a pigmented rash bilaterally which measures 4x5cm . It looks dry but is not associated with scaling , tenderness or discharge . Dermatological examination is otherwise unremarkable , as are remaining systems examinations .

Geoff ’ s past medical history includes osteoarthritis , constipation , gastro-oesophageal reflux disease , type 2 diabe- lesion is sent for histopathology with a view to identify a definitive diagnosis . This demonstrates papillomatosis and hyperkeratosis , in keeping with acanthosis nigricans .

Discussion

Diabetes may affect all organ systems , and the skin is no exception . 1 Acanthosis nigricans may be one such manifestation of diabetes . Although often asymptomatic , it is typically characterised by deep-brown hyperpigmentation with skin thickening and a velvety consistency , which may cause cosmetic concern . 2 Acanthosis nigricans is usually distributed symmetrically in skin folds , most commonly the neck and axilla . 2

Acanthosis nigricans is typically a cutaneous manifestation of underlying

Diabetes may affect all organ systems , and the skin is no exception .

tes , mild to moderate renal impairment	systemic disorders . 2 Rarely , it may pres-
and neck stiffness and pain as a result of	ent as an isolated dermatological con-
C3-T2 epidural abscess and osteomyelitis	dition . There are many potential causes
three years prior . For diabetes control , he	in addition to diabetes . It may be asso-
is taking insulin glargine 20 units nocte	ciated with other metabolic disorders ,
with insulin aspart six units three times daily . In the past , he took metformin , but	most commonly obesity , but also insulin resistance and hyperandrogenism . It	underlying insulin-resistant state . 3 The development of acanthosis nigricans ,	the 60- , 90- and 120-minute readings . If signs of hyperandrogenism are present ,
this was ceased two years ago because of his renal impairment . Differential diagnoses An initial diagnosis of bilateral axillary	may be a paraneoplastic manifestation , mainly of abdominal organ adenocarcinomas . 2 More rarely , it may be associated with autoimmune disorders and certain medications , including nicotinic acid , or	particularly in sites like the knuckles , may lead to accurate and opportunistic identification of people with metabolic risk . 3 Individuals with both established dia-	further investigations to find a possible cause are warranted . 4 These may include 24-hour urinary cortisol , serum total testosterone , dehydroepiandrosterone and gonadotropins . 4
fungal infection is made , with other dif-	be genetic or idiopathic . 2	betes and acanthosis nigricans require	A combination of lifestyle modifica-
ferential diagnoses being acanthosis nig-	Multiple factors can be involved in	higher insulin doses to control blood glu-	tion and pharmaceutical methods to pre-
ricans , inflammation associated with	development of acanthosis nigricans ,	cose levels in comparison with patients	dominantly improve insulin resistance
type 2 diabetes and non-melanoma skin cancer . Investigations and review A series of blood tests are ordered . Results are in the acceptable range apart from a fasting glucose of 14mmol / L ( normal 3-5.4 )	with insulin resistance the most frequent . Obesity is a significant cause of insulin resistance , but insulin resistance can also be seen in patients with type 2 diabetes , hypertension and dyslipidaemias . 3 The underlying pathophysiology driving the proliferation of keratinocytes	with diabetes who do not have this skin manifestation . 3 This is postulated to be a result of greater insulin resistance among those with acanthosis nigricans . 3 Diagnosis is usually clinical , but histological confirmation is warranted if there is any diagnostic uncertainty .	may aid management of this skin manifestation . Weight management , dietary changes and exercise have been shown to increase insulin sensitivity and aid management of acanthosis nigricans . 4 Pharmaceutical agents , including metformin , octreotide and other oral antihyperg-
and an HbA1c of 9.5 % ( normal < 6.5 %, tar-	and dermal fibroblasts in acanthosis nig-	Biopsies typically demonstrate digiti-	lycaemic agents may improve insulin
get < 7 %). As a result , a four-week course of clotrimazole / hydrocortisone 1 % cream is commenced , along with up-titration of	ricans is not fully understood . 4 Acanthosis nigricans is a recognised clinical marker of insulin resistance in	form papillomatosis , acanthosis , and soft hyperkeratosis . 4 Since acanthosis nigricans is a clue for hyperinsuli-	resistance and / or reduce hyperinsulinaemia . 3 Medications to specifically address the cutaneous appearance may be used
his insulin glargine to 24 units aiming to	established diabetes . However , even	naemia , it is recommended to perform	if cosmesis is a concern . Options include
improve his glycaemic control .	among those with normoglycaemia ,	a 75g oral glucose tolerance test , where	cholecalciferol or oral retinoids . 4
After four weeks , there is no sign of	acanthosis nigricans has a high specific-	hyperinsulinaemia can be diagnosed	Although acanthosis nigricans is
improvement . A punch biopsy of the	ity and positive predictive value for an	with two or more high insulin values at	one of the more common dermatologic

Australian Doctor 8th Nov Issue | Page 46

46 CLINICAL FOCUS

46 CLINICAL FOCUS

The skin ’ s the thing

GEOFF , a 79-year-old retiree , is a long-term aged care resident . The nursing staff report that he has had a red rash in both axillae for the past four months . Although this is not bothering Geoff , he wonders why it is lingering , despite treatment with a potent topical anti-inflammatory .