Formalin fixation destroys the antigenicity of the immune deposits. A separate biopsy must be provided which is sent to the laboratory in Michel’s Transport medium 

An incisional or punch biopsy may be bisected and half placed in formalin, the other in transport medium. Alternatively, two separate biopsies may be taken if clinically preferable. 

The technical procedure requires a reasonable amount of tissue. The two samples should be of approximately the same size.

Michel’s Transport Medium is available from the laboratory on request. It has a shelf life of up to six months when stored in the fridge. Once a specimen has been placed in the transport medium it should be sent to the laboratory. Specimens remain viable for seven days or longer in the medium and do not require urgent collection.

It is imperative that the Michel’s Transport Medium is not contaminated with formalin. The most common ways that this may occur are from forceps, having first placed half the sample in formalin, or by transposition of the container lids. The transport medium container lid is YELLOW.