A 54-year-old Woman with Myelofibrosis and Massive Hemothorax Due to Primary Extramedullary Hematopoiesis of the Pleura

Abstract

Extramedullary hematopoiesis, which represents ectopic blood cell production, is usually an incidental finding accompanying hematologic pathology. The liver and spleen are the most common sites of extramedullary hematopoiesis, but thoracic involvement is likewise observed. Pleural effusions in the setting of intrathoracic extramedullary hematopoiesis have been attributed to mechanical interactions between the pleural surface and neighboring paravertebral masses consisting of hematopoietic tissue. Rupture of these highly vascularized lesions into the adjacent pleural space has been the putative mechanism in cases complicated by hemothorax. Histologically proven instances of islets of extramedullary hematopoiesis occurring on the pleural surface itself are exceedingly rare. Our case of a patient with myelofibrosis and massive pleural effusion is only the third such example described in the literature and the second to result in a confirmed hemothorax requiring surgery. As expected, technetium-99m sulfur (Tc-99m sulfur) colloid scanning accurately localized sites of extramedullary hematopoiesis in our patient, and there was a salutary response to radiation therapy.

Keywords: extramedullary; hematopoiesis; hemothorax; myelofibrosis; pleural; radiation.

Figure 1. Left pleural effusion on chest X-ray

Portable plain radiograph of the chest showing a massive left pleural effusion (black star) with contralateral displacement of trachea (blue arrow)

Figure 2. Multi-loculated pleural effusion and active bleeding on CT angiogram

A) Coronal view from the computed tomography (CT) angiogram of the chest showing a multi-loculated pleural fluid collection in the left hemithorax (white arrows). B) Axial image from the CT angiogram showing extravasation of contrast (green arrow) compatible with active bleeding

Figure 3. Pleural biopsy with megakaryocytes seen with hematoxylin & eosin and immunostaining

A) Pleural biopsy section showing multiple megakaryocytes (green arrows) as well as an erythroid precursor (white arrow). Inset shows a different section containing a myeloid precursor (black arrow) (hematoxylin & eosin, original magnification x 400, inset x 100). B) Pleural tissue immuno-staining for CD61 (black arrows), which highlights megakaryocytes (original magnification x 400).

Figure 4. Increased uptake on SPECT/CT

Technetium-99m sulfur (Tc-99m sulfur) colloid single photon emission computed tomography/CT (SPECT/CT) axial fusion image showing increased uptake in the thorax (black arrows). Planar scintigraphy images (inset lower right) likewise demonstrate increased uptake in both the right and left hemithorax (red arrows) while highlighting the massive splenomegaly characteristic of myelofibrosis (asterisk)