Subcutaneous pseudomembranous fat necrosis: new observations/linkr>

Authors

  • Carlos Diaz-Cascajo,

    Corresponding author
    1. Center for Dermatopathology, Freiburg, Germany
      Carlos Diaz-Cascajo, M.D., Center for Dermatopathology, Postfach 1268,
      79012 Freiburg, Germany
      Tel. +49 761 31696
      Fax +49 761 39772
      e-mail Tiengen@t-online.de
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  • Susanna Borghi

    1. Center for Dermatopathology, Freiburg, Germany
    Search for more papers by this author

  • This study was presented at the 4th Joint Meeeting of the International Society of Dermatopathology (Washington D C, February 28th–March 1st, 2001).

Carlos Diaz-Cascajo, M.D., Center for Dermatopathology, Postfach 1268,
79012 Freiburg, Germany
Tel. +49 761 31696
Fax +49 761 39772
e-mail Tiengen@t-online.de

Abstract

Background: Pseudomembranous fat necrosis is a peculiar manifestation of necrosis of adipose tissue characterized by formation of pseudocystic cavities lined by crenulated membranes. The underlying mechanism for the formation of pseudomembranes is unknown and numerous hypotheses have been proposed. Despite divergent interpretations, most authors consider necrotic fat cells to be the anatomic substrate for the formation of pseudomembranes.

Methods: A total of 341 panniculitides were reviewed for the presence of pseudomembranous fat necrosis. The specific diagnoses were established after correlation of all available clinical and laboratory data with the histopathology. Special attention was given to the time in the evolution of the disease when the biopsy was taken. Additional immunohistochemical studies were performed in 12 cases.

Results: Thirty of 341 cases of different types of panniculitides were found to show pseudomembranous fat necrosis, namely: 10 of 15 cases of sclerosing panniculitis (lipodermatosclerosis), 6 of 95 cases of erythema nodosum, 7 of 34 cases of traumatic panniculitis, 1 of 7 cases of lupus panniculitis, 1 of 20 cases of erythema induratum Bazin (nodular vasculitis), 1 of 9 cases of necrobiosis lipoidica, 1 of 4 cases of sclerotic lipogranuloma, 1 of 9 cases of infectious panniculitis (erysipelas), 1 of 2 cases of pancreatic panniculitis, and 1 of 4 cases of subcutaneous sarcoidosis. Pseudomembranous fat necrosis labelled strongly for the histiocytic markers CD68 and lysozyme.

Conclusions: Our series provides data suggesting that pseudomembranous fat necrosis represents a dynamic process that varies according to the evolution of the lesion at the time of the biopsy. In biopsies taken from early foci of panniculitides pseudomembranes show vescicular or picnotic nuclei. Later, pseudomembranes retain their crenulated appearance but lack nuclear elements. Furthermore, we present histopathologic, histochemical, and immunohistochemical evidence that pseudomembranous fat necrosis results from the interaction of residual products of disintegrated fat cells and macrophages. Histiocytic markers such as CD68 and lysozyme may be used as reliable tools in order to detect pseudomembranes in panniculitides.

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