Case Number : Case 1582 - 19 July Posted By: Guest

panniculitis with membranous fat necrosis?

ddx includes few conditions like EN & traumatic fat necrosis, etc

Mixed pattern (lobular and septal) panniculite with lipomembranous alteration. I think this is probably a Facticial or Traumatic Panniculitis. I like to use polarised light in these cases to look for foreign body.

My interpretation was that this was mainly lobular panniculitis with membranous fat necrosis. I agree that there is important fibrosis of the septae. I also agree with the differentials considered and would like to add a late pancreatic panniculitis as ghost adypocytes can dissapear with time, the context of abdominal surgery (pancreatic cancer, chronic pancreatitis?) if adequate could also fit.

Difficult! Does not look like pancreatic.  Incidentally polarising can show small crystalline deposits in pancreactic fat necrosis.  These also don't look particularly like lipomembranous fat necrosis to me.  It reminds me more of Miescher's radial granulomas.  I think EN can have these giant cells and present with an apparently lobular predominance occasionally.  We can't really see the centre of the lobules in these images. Factitial panniculitis does need considering and agree with polarising.  My "gut" says EN.

I'm sure there is a lipomembranous fat necrosis. Not sure about the giant cell foreign body like granulomatous component.

Great discussion. Clinically the lesions fit with erythema nodosum and we thought the histology was fine for it as well as EN can have a variety of different appearances. No polarizable foreign material was identified. We thought factitial panniculitis remained in the differential but the clinician was not as convinced of this clinically.

Great case! have to admit that EN was not my high on my list of differentials! I think its a good learning point that EN can have quite a variable histology and not to dismiss it if pattern of inflammation is too lobulocentric.

May I suggest reviewing cases 552 and 1378 for examples of lipomembranous fat necrosis.