Nodular melanoma presenting as an exophytic subungual mass.

Despite being recognised and reported in the literature for decades, subungual melanoma of the foot remains a diagnostic pitfall, with it commonly being mistaken for benign conditions. We present an interesting case of delayed diagnosis of subungual melanoma of the hallux that was misdiagnosed in the community for over one year. With melanoma being the fourth most commonly diagnosed cancer in Australia in 2013, this case serves as a reminder to all clinicians about the importance of maintaining a high index of suspicion for melanoma of the foot.

Toxicity thresholds for juvenile freshwater mussels Echyridella menziesii and crayfish Paranephrops planifrons, after acute or chronic exposure to Microcystis sp.

Survival of juvenile freshwater mussels (Echyridella menziesii (Gray, 1843) formerly known as Hyridella menziesi) and crayfish (Paranephrops planifrons, White, 1842) decreased after four days exposure to microcystin-containing cell-free extracts (MCFE) of Microcystis sp. at concentrations typical of severe cyanobacterial blooms. Crayfish survival was 100, 80, and 50% in microcystin concentrations of 1339, 2426, and 11146 µg L(-1) respectively, and shade- and shelter-seeking behavior was negatively affected when concentrations were ≥2426 µg L(-1) . Mussel survival decreased to 92% and reburial rates decreased to 16% after exposure for 96 h to MCFE containing microcystins at concentrations of 5300 µg L(-1) . Crayfish survival was 100% when fed freeze-dried Microcystis sp. incorporated into an artificial diet (6-100 µg microcystin kg(-1) ww) at dietary doses from 0.03 to 0.55 µg g(-1) body weight d(-1) for 27 days. Specific growth rate was significantly lower in crayfish fed ≥0.15 µg g(-1) body weight day(-1) compared with controls, but not compared with a diet incorporating nontoxic cyanobacteria. Microcystins accumulated preferentially in crayfish hepatopancreas and mussel digesta as MCFE or dietary concentrations increased. These laboratory data indicate that, assuming dissolved oxygen concentrations remain adequate, and no simultaneous exposure to live Microcystis sp. cells, cell-free microcystins will only be a significant stressor to juvenile crayfish and mussels in severe Microcystis sp. blooms. In contrast, crayfish were negatively affected by relatively low concentrations of microcystins in artificial diets compared with those measured locally in benthic cyanobacterial mats.