A retrospective cohort study of melanoma prevalence stratified by body site in a Regional Australian Population 1994-2017: Site-specific protective mechanisms.

BACKGROUND: Australia has the highest incidence of cutaneous melanoma worldwide. Previous studies have identified some body areas (forearms and dorsal hands) have lower rates of melanoma than expected when compared with other similarly exposed areas, leading to the suggestion that endogenous immunological protective mechanisms in certain body sites may exist. AIMS AND METHODS: We hypothesise that examination of melanoma by body site in a regional Australian setting would demonstrate no significant variation in the incidence of melanoma across highly sun exposed areas including the head and neck and upper limbs. Results were stratified by body site and further examined by univariate correlation analysis by gender, age, body site, Breslow thickness and subtype. Polytomous logistic regression was used to test the difference in risk factors by location of melanoma. RESULTS: A total of 772 melanomas were included in the analysis. Melanomas of the upper limb were more likely to affect females (OR = 2.415 95%CI: 1.433-4.072) and more likely to be thinner than other body sites. Compared to other international studies, statistically significant decreased rates of melanoma were seen on the upper limb compared to other areas of the body (X2  = 16.29, P < 0.001). Examination of sites of melanoma on the upper limb showed significantly decreased rate on the distal upper limb given relative body surface areas (X2  = 6.30 P = 0.04). DISCUSSION AND CONCLUSIONS: Our study was limited by its retrospective nature, and the findings require validation in a larger prospective cohort. Further exploration of such mechanisms may lead to new insights into the immunological mechanisms surrounding cutaneous melanoma.

Queensland tick typhus in rural New South Wales.

We report five cases of Rickettsia australis infection from southern coastal New South Wales, Australia. All patients presented with a cutaneous eruption of erythematous papules and pustules and systemic features of malaise, headache, lymphadenopathy and myalgia. Acute kidney injury (AKI) was present in two of five cases and one of five cases had acute delirium. Improvement was only seen after treatment with doxycycline 100 mg b.i.d. Positive serology for R. australis was present in four of five cases and a positive polymerase chain reaction (PCR) was seen in one of five cases. Histology showed varying features, from neutrophilic vasculitis to Sweet's syndrome and lymphocytic vasculitis. Recent significant advances in the diagnosis of R. australis infection include an eschar swab or biopsy PCR and isolation of specific Rickettsia on serology. These investigations should be considered in the presence of any of the following features: eschar at site of a tick bite or lymphadenopathy and fever with an eruption of erythematous papules and pustules.

Cryptococcosis presenting as upper limb cellulitis and ulceration: a case series.

We report four cases of cryptococcosis presenting as upper limb cellulitis or ulceration, or both. Three of the four patients were on long-term prednisolone therapy at the time of presentation. In each case, the diagnosis of cryptococcosis was established by a biopsy of the skin. Only one of the four patients had conclusive evidence of disseminated disease. Our cases highlight the importance of skin biopsy in immunosuppressed individuals presenting with cellulitis, particularly when the cellulitis occurs in an atypical location and when the clinical condition fails to respond to standard antibacterial therapy.

Porphyria cutanea tarda in south-east New South Wales.

Thirteen patients with porphyria cutanea tarda diagnosed between 1994 and 2000 were reviewed to evaluate the precipitating factors and associations of porphyria cutanea tarda in a regional area of coastal and rural NSW. The majority had more than one precipitating factor, with excess alcohol intake, mutations in the haemochromatosis gene, chronic hepatitis C infection and oestrogen therapy being the most common. Antibodies to the hepatitis C virus were detected in 25% and these patients presented at a younger age. Of the patients tested for the two known haemochromatosis gene mutations, six (46%) had at least one copy of the C282Y mutation. Two (15%) patients were homozygous for the C282Y mutation and two (15%) were compound heterozygous for the C282Y and H63D mutations. All patients responded to venesection, which is the treatment of choice for the majority of patients with porphyria cutanea tarda.