Caecal mass in a septic 72-year-old woman

A 72-year-old woman immunosuppressed for previous renal transplantation was admitted with worsening abdominal pain and constipation. Her medical history is significant for diabetic nephropathy, pancreatitis and sigmoidectomy for diverticulitis. On examination, the patient appeared septic with a temperature of 38.1, chills, tachypnoea and fluctuating blood pressure requiring intravenous fluid resuscitation. Admission blood tests showed raised inflammatory markers (white cell count 15.8×10 9/L and C-reactive protein 220 mg/L). An intravenous contrast-enhanced CT of the abdomen/pelvis revealed a caecal mass with surrounding mesenteric lymphadenopathy—highly suggestive of malignancy (see figure 1). Differential diagnoses considered at this point were a primary colonic tumour, post-transplant lymphoproliferative disease, metastasis or infective process such as diverticular abscess or tuberculosis. Blood cultures grew wild-type Escherichia coli, and the patient required an emergency laparotomy with ileocaecal resection for uncontrolled sepsis. The excised specimen was sent for histopathology which did not show neoplastic disease or cancer. However, it revealed a fibroinflammatory process consisting of large sheets of histiocytes with abundant faintly eosinophilic cytoplasm and widespread intracytoplasmic targetoid inclusions. Positive staining with Von Kossa, Perl’s and H&E stains (see figures 2–4) revealed these basophilic inclusions to be Michaelis-Gutmann bodies, pathognomonic for the diagnosis.