Answer to Quiz No. 109 dated 15 Oct 2017
Extramedullary hematopoiesis
Findings
Chest radiograph shows multiple lobulated bilateral paravertebral lesions with well-defined lateral margins. CT topogram shows the lobulated bilateral paravertebral lesions and splenomegaly. Axial and coronal images of contrast enhanced CT thorax revealed multiple lobulated hypodense lesions in bilateral paravertebral locations with an average attenuation of ~ 35 HU. These lesions extend from around T2 to diaphragmatic level. The spleen is enlarged (15cm), with multiple rounded hypodense ~ 10mm sized lesions. There is mild diffuse increase in bone density. Incidental finding - Left renal lower pole cortical cyst. These findings are suggestive of a marrow infiltrative condition like myelodysplastic or myeloproliferative condition with associated extramedullary hematopoiesis. Bone marrow biopsy was suggested which confirmed myelodysplastic syndrome.
Discussion
Extramedullary hematopoiesis (EMH) is the proliferation of hematopoietic tissue outside the bone marrow, typically seen in patients with chronic haemolytic anemia, such as thalassemia and sickle cell disease, or myeloproliferative neoplasms, especially primary myelofibrosis, and rarely with myelodysplastic syndrome. They represent the reactive and/or compensatory expansion of hematopoietic tissue outside the bone marrow in patients with anaemia or an abnormal bone marrow function. Although any organ can be involved, the liver and the spleen are the sites most commonly affected. Extramedullary haematopoiesis less commonly affects the pleura, lungs, gastrointestinal tract, breast, skin, brain, kidneys, and adrenal glands. Thoracic involvement is less common. When present, they can be seen as posterior mediastinal masses. Occasionally, these masses can appear in the anterior mediastinum or in the pleura. Radiographically, intrathoracic EMH usually presents as multiple paravertebral masses, usually bilateral, lobulated, with well-defined borders, and without accompanying calcifications or bone erosion. This is important for the differential diagnosis of paravertebral neurofibromas, which usually have accompanying bone alterations. However, evidence of bone lesions related to the underlying disease is a common finding. On chest radiographs, such masses usually present as lobulated, double-contour cardiac silhouette in frontal view, as well as lobulated mass projected over the lower vertebral bodies in lateral view. These lesions are typically hypermetabolic and are 18-FDG avid on PET-CT.
References
1. Sawada H, Higuchi T, Koyamada R, Okada S. Myelodysplastic Syndrome Developing Presacral Extramedullary Hematopoiesis with Atypical MRI Findings. Internal Medicine. 2017;56(10):1213-1217. 2. Choi H, David CL, Katz RL et-al. Case 69: extramedullary hematopoiesis. Radiology. 2004;231 (1): 52-6. 3. Gumbs RV, Higginbotham-ford EA, Teal JS et-al. Thoracic extramedullary hematopoiesis in sickle-cell disease. AJR Am J Roentgenol. 1987;149 (5): 889-93. 4. Marchiori E, Escuissato DL, Irion KL, Zanetti G, Rodrigues RS, Meirelles Gde S, Hochhegger B: Extramedullary hematopoiesis: findings on computed tomography scans of the chest in 6 patients. J Bras Pneumol. 2008; 34 (10): 812-816.
Findings
Chest radiograph shows multiple lobulated bilateral paravertebral lesions with well-defined lateral margins. CT topogram shows the lobulated bilateral paravertebral lesions and splenomegaly. Axial and coronal images of contrast enhanced CT thorax revealed multiple lobulated hypodense lesions in bilateral paravertebral locations with an average attenuation of ~ 35 HU. These lesions extend from around T2 to diaphragmatic level. The spleen is enlarged (15cm), with multiple rounded hypodense ~ 10mm sized lesions. There is mild diffuse increase in bone density. Incidental finding - Left renal lower pole cortical cyst. These findings are suggestive of a marrow infiltrative condition like myelodysplastic or myeloproliferative condition with associated extramedullary hematopoiesis. Bone marrow biopsy was suggested which confirmed myelodysplastic syndrome.
Discussion
Extramedullary hematopoiesis (EMH) is the proliferation of hematopoietic tissue outside the bone marrow, typically seen in patients with chronic haemolytic anemia, such as thalassemia and sickle cell disease, or myeloproliferative neoplasms, especially primary myelofibrosis, and rarely with myelodysplastic syndrome. They represent the reactive and/or compensatory expansion of hematopoietic tissue outside the bone marrow in patients with anaemia or an abnormal bone marrow function. Although any organ can be involved, the liver and the spleen are the sites most commonly affected. Extramedullary haematopoiesis less commonly affects the pleura, lungs, gastrointestinal tract, breast, skin, brain, kidneys, and adrenal glands. Thoracic involvement is less common. When present, they can be seen as posterior mediastinal masses. Occasionally, these masses can appear in the anterior mediastinum or in the pleura. Radiographically, intrathoracic EMH usually presents as multiple paravertebral masses, usually bilateral, lobulated, with well-defined borders, and without accompanying calcifications or bone erosion. This is important for the differential diagnosis of paravertebral neurofibromas, which usually have accompanying bone alterations. However, evidence of bone lesions related to the underlying disease is a common finding. On chest radiographs, such masses usually present as lobulated, double-contour cardiac silhouette in frontal view, as well as lobulated mass projected over the lower vertebral bodies in lateral view. These lesions are typically hypermetabolic and are 18-FDG avid on PET-CT.
References
1. Sawada H, Higuchi T, Koyamada R, Okada S. Myelodysplastic Syndrome Developing Presacral Extramedullary Hematopoiesis with Atypical MRI Findings. Internal Medicine. 2017;56(10):1213-1217. 2. Choi H, David CL, Katz RL et-al. Case 69: extramedullary hematopoiesis. Radiology. 2004;231 (1): 52-6. 3. Gumbs RV, Higginbotham-ford EA, Teal JS et-al. Thoracic extramedullary hematopoiesis in sickle-cell disease. AJR Am J Roentgenol. 1987;149 (5): 889-93. 4. Marchiori E, Escuissato DL, Irion KL, Zanetti G, Rodrigues RS, Meirelles Gde S, Hochhegger B: Extramedullary hematopoiesis: findings on computed tomography scans of the chest in 6 patients. J Bras Pneumol. 2008; 34 (10): 812-816.
