Best practice in diagnosis and follow-up of melanoma is slipping in Australia, leading dermatologists warn.

They say clinical practice is diverging from national guidelines, with rising rates of shave rather than excisional biopsy and reduced risk stratification using sentinel lymph node biopsy.

The proportion of shave biopsies to diagnose invasive melanoma more than doubled in Victoria over a decade, according to a study in the Medical Journal of Australia.

Although the technique may be promoted for better cosmesis and being cheaper, it is associated with staging inaccuracy, said specialists in an accompanying editorial.