Which histologic findings are characteristic of cutaneous cholesterol emboli (CCE)?

Updated: Apr 12, 2021
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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Answer

When examined with polarized light, cholesterol crystals in frozen section appear as birefringent rhomboids. They can also be identified by the Schultz modification of the Lieberman-Burchard reaction for cholesterol. Crystals are green within a few minutes and then brown at 30 minutes. Paraffin embedding used in routine histologic processing dissolves cholesterol crystals, replacing them with characteristic biconvex or lenticular clefts or spaces.

Emboli have been observed in the lumina of arteries ranging from 55-900 mm in external diameter but favor vessels in the 150- to 200-µm range. Initially, cholesterol clefts with or without hyaline material and rarely an aggregate of lipid-filled histiocytes are observed. Thrombosis superimposed on the embolus is variable. Shortly thereafter, reactive hyperplasia of the intima occurs with dense infiltration of the media and adventitia or surrounding tissue with neutrophils and, occasionally, eosinophils. Fibrinoid necrosis of the vessel walls and interruption of the internal elastic membrane are also variable findings.

In older lesions, the infiltrate is replaced by mononuclear and foreign body giant cells and prominent fibrosis. The crystals may persist, disappear, or extrude through vessel walls. In heavily infarcted areas, coagulative and early liquefactive necrosis of the epidermis, dermis, and panniculus may be observed.

While generally considered pathognomonic for CCE, the presence of intravascular cholesterol crystals has recently been described in biopsy and excision specimens of nonmelanotic skin cancers from patients with no evidence of CCE. The authors of one paper suggest that in such cases, this finding may be artifactual and perhaps related to wound healing.


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