Case Number : Case 4129 - 17 Nov 2022 Posted By: Saleem Taibjee

Parakeratosis, mild spongiosis, individual apopototic keratinocytes in the epidermis and a dermal infiltrate that contains a few eosinophils are the features that suggest measles. Has the child missed his MMR vaccine?

Drug reaction vs exanthem. Many mast cells i guess! Does the pt have an underlying mastocytosis?

Mixed pattern of predominantly spongiotic and focal interface changes at the edge ofbiopsy with numerous eosinophils in dermis.

The child is pyrexial and one would normally do not a biopsy in a child for viral exanthem unless there is other possibilities like severe adverse drug reaction. DRESS/DIHS is a possibility, it is a mimicker of sepsis and histology needs to be correlated with history of exposure to relevant drug exposure few weeks before, eosinophils counts, LFTs and other parameters to clarify if the required threshold of diagnostic criteria are met or not.

From pure histologic prospective, viral exanthem can share similar features. 

Drug reaction or viral exanthem. Tough to differentiate between the two on histology. 

On 23/11/2022 at 11:34, Meenakshi Batrani said:

Drug reaction or viral exanthem. Tough to differentiate between the two on histology. 

Agrere. 

Yes, brilliant, Saman. This was a recent case of DRESS syndrome. Of course, as many of you have alluded to, the histology is not specific and it requires clinical correlation. But DRESS is worth considering in a patient with a rash and persistent pyrexia despite antibiotics. In this case it was probably triggered by anticonvulsant therapy which is a group of drugs well known to cause DRESS, and worth remembering that there can be a latency of a few weeks before onset with DRESS. 
BW, Saleem