Answer to Image of the Month July 2015

Submitted by Poonam Panjwani and Rajalakshmi T


Artefactual changes due to freezing

While it is imperative for a dermatopathologist to recognise various disease patterns under the microscope, it is equally important to be aware of artefactual changes that mimic authentic disease.

The biopsy shows extensive vacuoles of varying sizes within a variety of cell types: keratinocytes, melanocytes, sebocytes and also within the collagen. The extent and nature of vacuoles do not conform to any known entity. The biopsy was done to rule out Langerhans cell histiocytosis in the child. Slight hypergranulosis and a few dermal eosinophils are seen, which do not convey specificity.

Freezing artefact is seen when tissue is subjected to slow freezing, it is usually not noted when tissue is frozen rapidly. It occurs if the sample is dropped in very cold fixative or is kept in cold conditions for prolonged periods. This is particularly true of biopsies done before weekends (which is what occurred in the present case), when the sample may be inadvertently kept in the fridge. It is vital to give clear instructions regarding sample storage, if such a situation is foreseen.


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