Secondary extramedullary plasmacytoma of sigmoid colon in a patient with multiple myeloma: a case report

Abstract

Background: Extramedullary plasmacytoma is an uncommon tumor that most often involves the nasopharynx or upper respiratory tract. Extramedullary plasmacytoma is a type of plasma cell neoplasm that can present as a primary tumor or secondary to another plasma cell neoplasm, such as multiple myeloma. Secondary extramedullary plasmacytoma is usually noted in the advanced stages of the disease. Involvement of the gastrointestinal tract occurs in approximately 10% of cases.

Case presentation: A 71-year-old Caucasian woman with known diverticular disease of the colon and multiple myeloma diagnosed 3 years previously, with monoclonal bands of immunoglobulin A, lambda light chains, and multiple osteolytic lesions, presented to our hospital with abdominal pain, abdominal discomfort, and pneumoperitoneum. She underwent left colectomy for diverticulitis with perforation, and an extramedullary secondary colonic plasmacytoma was found in histopathological examination of the sigmoid colon.

Conclusions: Plasmacytoma is known to occur in extraosseous sites. The stomach and small intestine are the most commonly involved sites in the gastrointestinal tract. Secondary extramedullary plasmacytoma of the colon is rare. Colonic plasmacytoma may have varying clinical presentations, such as inflammatory bowel disease and multiple colonic strictures. Although these cases are rare, treating physicians as well as radiologists, pathologists, and surgeons should be aware of this entity.

Keywords: Multiple myeloma; Oncology; Secondary extramedullary plasmacytoma; Sigmoid colon.

Fig. 1

Axial computed tomography with no enhancement depicts a mass of soft tissue density in the anatomical area of the sigmoid colon and another compact lesion of soft tissue density on the left lateral wall of the minor pelvis. Presence of diverticula can be seen

Fig. 2

Pneumoperitoneum and osteolytic lesion on the left side of the pelvis with osteosclerotic component

Fig. 3

Axial computed tomography after administration of intravenous contrast shows enhancement of the lesions

Fig. 4

Coronal computed tomography of the distended colon and pneumoperitoneum

Fig. 5

Surgical specimen of extramedullary plasmacytoma in the sigmoid colon

Fig. 6

Microscopic evaluation (H&E stain, original magnification 400×). Large oval cells, consisting of a round nucleus in eccentric position with coarse chromatin, protruding nucleolus, and enough cytoplasm

Fig. 7

Microscopic evaluation (H&E stain, original magnification 100×). The neoplasm densely infiltrates the muscular wall of the intestine and the pericolic fat, without reaching the surface of the serum and without infiltrating the mucosa, which has severe ischemic lesions

Fig. 8

IHC analysis (CD138 stain, original magnification 400×) shows that the tumor cells are CD138⁺ with a few keratins

Fig. 9

IHC analysis (light chain, original magnification 400×) for both kappa-light and lambda-light chains give an unreliable effect owing to a very high substrate material