S10C5P3-3: At higher magnification, migratory histiocytes are admixed among the neutrophils. Fragments of red blood cells also are present among the neutrophils (“Weber-Christian disease”).

S10C5P3-4: This lesion shows lobular and septal changes. The combination is common and, generally, the lobular component would be assigned precedence in the classification. A septum coursing diagonally from the right to the bottom of the field is widened and fibrotic.

The vacuoles of the lobules have a distribution in keeping with a population of lipocytes, but they vary in size. Some are larger than normal lipocytes and irregular in outline. Some of the larger defects are associated with infiltrates of lymphoid cells in the adjacent fibrous tissue (just above center of field). To the left above the center of the field, there is an increased amount of interstitial matrix among the vacuoles. The variabiltiy in sizes of vacuoles, the irregular fibrosing patterns, and the spotty infiltrates of inflammatory cells are features favoring a diagnosis of panniculitis (lobular and septal). The patterns are those of calcifying panniculitis of renal failure. The general pallor and acidophilia is evidence of necrosis; the lipocytes are necrotic.

S10C5P3-5: At a higher magnification, the vacuoles are not viable lipocytes; there are no nuclei associated with the vacuoles. A small vessel near the upper, left margin contains a thrombus. The meshwork of red fibrils among the vacuoles is fibrin. There are extravasated red blood cells, and there are fragments of nuclei (fragmented nuclei of inflammatory cells). The tissue is dead. The changes would support an interpretation that the initial insult was an occlusion of small vessels ( calcifying panniculitis of renal failure and dialysis).

S10C5P3-6: Lipocytes are dead. A vessel courses across the field; it shows fibrinoid necrosis and thrombosis. The wall of the vessel is thickened and hyalinized. There are fragments of nuclear debris. The changes are those of a coagulopathy (calcifying panniculitis).

S10C5P3-7: The central vessel shows calcification of the intima. The calcification extends to the interface with a thin muscular coat. The neighboring lipocytes are dead. Neighboring small vessels (green arrows) show thrombosis and fibrinoid necrosis (“calciphylaxis”).

S10C5P3-8: This small, muscular vessel shows eccentric, fibro-mucinous hyperplasia of the intima and a narrowed lumen. A ring of calcium has deposited at the interface between intima and media. The width of the media of the vessel would suggest that the vessel is a vein (“calciphylaxis”). The calcification is at the level of the internal elastic lamina.