Unilateral intrathoracic extramedullary hematopoiesis (ITEMH) is an extremely rare condition characterized by the abnormal proliferation of hematopoietic tissue outside the bone marrow. Although most reported cases of ITEMH are associated with underlying hematological disorders such as myelofibrosis or thalassemia, our case is unique as it occurred in the absence of any known hematological abnormalities. This suggests that there may be other underlying factors or mechanisms contributing to the development of ITEMH, which require further investigation.
The clinical presentation of ITEMH can mimic other intrathoracic masses, leading to misdiagnosis and delays in appropriate management. In our case, the patient initially presented with respiratory symptoms and imaging studies suggested a mediastinal mass compressing the left lung. This highlights the importance of thorough evaluation and considering ITEMH in the differential diagnosis, even in patients without a history of hematological disorders.
Surgical resection, as performed in our case, can be curative and alleviate symptoms, resulting in a favorable prognosis. The excised mass in our case showed well-defined borders and was composed of hematopoietic tissue with evidence of maturation, confirming the diagnosis of ITEMH. Immunohistochemical staining further supported the presence of CD34-positive hematopoietic cells. The absence of malignancy in the histopathological examination indicates the benign nature of ITEMH in our case.
Histopathological Examination:
Microscopic examination of the excised specimen revealed a well-circumscribed mass measuring 5 cm in greatest dimension. The mass was composed of hematopoietic tissue, including mature and immature myeloid and erythroid elements, with evidence of hematopoietic cell maturation. No evidence of malignancy was identified. Immunohistochemical staining demonstrated the presence of CD34-positive hematopoietic cells, further supporting the diagnosis of intrathoracic extramedullary hematopoiesis.
The role of adjuvant therapies, such as radiotherapy or chemotherapy, in the management of ITEMH remains uncertain due to the limited number of reported cases and lack of consensus guidelines. The rarity of ITEMH poses challenges in conducting large-scale studies to establish optimal treatment strategies and long-term outcomes. Further research is needed to investigate the underlying mechanisms of ITEMH development, identify potential risk factors, and determine the efficacy of adjuvant therapies.
Follow-up and Outcome:
Postoperatively, the patient experienced a significant improvement in respiratory symptoms, with resolution of dyspnea and chest pain. Chest radiography and CT scans performed during follow-up visits at 3 months, 6 months, and 1 year postoperatively showed no evidence of recurrent or residual masses. Laboratory investigations, including complete blood count, peripheral blood smear, and bone marrow aspiration, did not reveal any underlying hematological abnormalities, ruling out secondary causes of intrathoracic extramedullary hematopoiesis.
Long-term follow-up is essential for monitoring potential recurrence or progression of ITEMH. This supports the curative potential of surgical resection in localized ITEMH.
Increasing awareness among clinicians about the existence of ITEMH and its clinical and radiological characteristics is crucial for early recognition and appropriate management. Reporting and documenting rare cases, such as ours, contribute to expanding the existing knowledge base and improving understanding of this rare tumor condition.