Magnetic resonance imaging features of intrahepatic extramedullary hematopoiesis: Three case reports

Abstract

Background: Extramedullary hematopoiesis rarely occurs within the liver alone, and is easily misdiagnosed. The radiological literature on this disease is exclusively case reports. There is a paucity of literature on the role of magnetic resonance imaging (MRI). The most common imaging modalities used are computed tomography and ultrasound. This report aims to provide more data on the appearance of extramedullary hematopoiesis using MRI to help radiologists establish the diagnosis.

Case summary: Three patients (one male and two females) were incidentally found to have a hepatic mass or nodule, without hepatomegaly or splenomegaly. Laboratory tests including liver function, serum hepatic tumor markers, and hepatitis serologic markers were normal. On MRI scans, all lesions showed lower signal intensity on in-phase images than on out-phase images. One case showed changes in signal intensity on T2 weighted images (WI) and diffusion WI, which shifted from hyperintensity to hypointensity with size enlargement between two rounds of imaging examination. These lesions exhibited different enhancement patterns on dynamic contrast enhancement series.

Conclusion: The MRI signal change and in-/out-phase image might provide useful information and help radiologists establish the diagnosis of intrahepatic extramedullary hematopoiesis.

Keywords: Case report; Extramedullary hematopoiesis; Liver; Magnetic resonance imaging; Signal intensity.

Figure 1

An intrahepatic mass (arrow) in segment VIII was found in a 50-year-old female. A: On unenhanced computed tomography, the lesion was heterogeneously hypodense, with hyperdense foci in the central area; B: The lesion was heterogeneously hyperdense in the arterial phase; C and D: Progressive enhancement in the portal venous (C) and delayed phases (D); E-K: On magnetic resonance imaging, the lesion was heterogeneously hyperintense on T2 weighted image (WI), T2WI-fat saturation (FS) (E and F) and diffusion weighted imaging (DWI) (G), isointense on the apparent diffusion coefficient map (H), hypointense on T1WI-FS (I), avid enhancement in the arterial phase (J) and persistent enhancement in the delayed phase (K); L-R: Corresponding follow-up images five months later showed that the lesion size had increased. Signal drop was seen on the in-phase (L) compared with the out-phase (M) image. The lesion was heterogeneously hypointense on T2WI-FS (N) and DWI (O), homogeneously hypointense on T1WI-FS (P), and showed hypervascular enhancement with delayed enhancement in the arterial (Q) and delayed phase (R), respectively. The surgical pathologic diagnosis was intrahepatic extramedullary hematopoiesis.

Figure 2

A 30-year-old female diagnosed with intrahepatic extramedullary hematopoiesis was confirmed by biopsy. A and B: The lesion (arrow) located in the subcapsular of segment VI/VII was slightly hyperintense on T2 weighted image (WI)-fat saturation (FS) (A) and slightly hypointense on T1WI-FS (B); C-E: The lesion showed a lower signal intensity on the in-phase (C) than on the out-phase (D) image, and signal loss on susceptibility weighted imaging (E); F-H: In dynamic series, the lesion was mildly enhanced in the arterial phase (F), with areas of progressive and prolonged enhancement in the portal venous (G) and delayed phases (H).

Figure 3

A 52-year-old male diagnosed with intrahepatic extramedullary hematopoiesis was confirmed by resection. A-D: The lesion located in segment V/VIII (arrow) showed lower signal intensity on the in-phase (A) than on the out-phase (B) image, as opposed to another lesion (the same patient) in segment IV (arrowhead, the surgical pathologic diagnosis was angioleiomyolipoma), which showed higher signal intensity on the in-phase (C) than on the out-phase (D) image; E-H: The lesion (arrow) showed high signal intensity on T2 weighted image-fat saturation (E), with intense enhancement in the arterial phase (F), and was relatively hypointense in the transitional phase (G) and hepatobiliary phase (H).

Figure 4

Intrahepatic extramedullary hematopoiesis in the same patient shown in figure 1. A: On the photomicrograph (hematoxylin and eosin staining; × 200), megakaryocytes and erythroid cells were scattered within the surgical specimen; B-D: Immunohistochemical staining using CD235 (B), CD61 (C) and MPO (D) markers (× 40) revealed that the cells were positive (brown color) for these markers, respectively.

Figure 5

Intrahepatic extramedullary hematopoiesis in the same patient shown in figure 3. A: Photograph of the specimen showed the lobular and solid nature of the resected hepatic mass (segment V/VIII), without areas of necrosis and hemorrhage; B: On the photomicrograph (hematoxylin and eosin staining; × 200), granulocytes, megakaryocytes, adipocytes and erythrocytes were distributed within the surgical specimen; C-E: Immunohistochemical staining using CD235 (C), CD61 (D) and MPO (E) markers (× 40) revealed that the cells were positive (brown color) for these markers, respectively.