Flea-Borne Typhus Causing Hemophagocytic Lymphohistiocytosis: An Autopsy Case

Abstract

Infection with members of the order Rickettsiales (the genera Rickettsia, Anaplasma, Orientia, and Ehrlichia) is known to cause hemophagocytic lymphohistiocytosis (HLH). The literature is scant on flea-borne typhus (FBT) being implicated in this process. We present a case of autopsy-proven HLH caused by FBT in a 71-year-old diabetic female who was initially suspected of having diabetic ketoacidosis who rapidly suffered decompensated multi-organ failure. Although she was suspected of having FBT and HLH pre-mortem, due to her rapid progression to multi-organ failure, she was transitioned to comfort care by her family five days after admission. A literature search yielded five other cases of HLH secondary to FBT, which are analyzed in this review. The literature on HLH occurring with infection due to other members of the order Rickettsiales is also surveyed.

Keywords: Rickettsia felis; Rickettsia typhi; autopsy; fatal; flea-borne typhus; hemophagocytic lymphohistiocytosis.

Figure 1

(a) Liver with portal hemophagocytosis demonstrated by histiocytes engulfing small lymphocytes (hematoxylin and eosin (H&E), 400×); (b) CD68 immunohisto-chemical stain highlights hemophagocytotic histiocytes in the liver (400×).

Figure 2

(a) Mediastinal lymph node with non-neoplastic activated histiocytes that exhibit hemophagocytosis (H&E, 400×); (b) CD68 immunohistochemical stain demonstrates hemophagocytotic histiocytes containing small lymphocytes in a mediastinal lymph node (CD68, 400×).

Figure 3

(a) Histiocytes engulfing small lymphocytes in the spleen (H&E, 400×; (b) Bone marrow infiltration by non-neoplastic histiocytes that display hemophagocytosis (H&E, 400×).