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AN UNUSUAL CASE OF DYSPNEA: MYELOID SARCOMA

      TOPIC: Pulmonary Manifestations of Systemic Disease
      TYPE: Medical Student/Resident Case Reports
      INTRODUCTION: Myeloid sarcoma (MS) is a rare extramedullary tumor recognized as a solid tumor equivalent of acute myeloid leukemia (AML). It is often accompanied by AML, but in rare instances presents as an isolated tumor without peripheral involvement in the blood or marrow. It has been found and described in case reports in nearly every organ, with no seeming predisposition for a particular one and extremely varied presentations. It presents a diagnostic dilemma due to its ability to present in any tissue with nonspecific symptoms and given its high mortality, delay in diagnosis tends to exacerbates poor outcomes.
      CASE PRESENTATION: A healthy 40 year old male presented to the ED for complaint of worsening dyspnea over 4 weeks. His symptoms were not exertional, and he denied cough, fever, chest pain, orthopnea, or edema. He was tachycardic and hypoxic to 82% on room air. CTA of the chest revealed a periaortic and posterior mediastinal mass measuring 9.6x6x17.8cm causing mass effect on the esophagus and left atrium and large bilateral pleural effusions. Thoracentesis was performed for diagnostic and therapeutic benefit however rapidly reaccumulated. Cytology was repeatedly performed and reviewed by several pathologists reporting rare amount of atypical cells, not further classified. Further pleural studies were unremarkable. IR biopsy and pathological report of the mass revealed diagnosis of myeloid sarcoma. Bone marrow biopsy was negative for AML, and cytogenetics demonstrated t(8:21). Patient underwent induction chemotherapy with traditional 7+3 (cytarabine and anthracycline), intrathecal methotrexate, and later 3 cycles HiDAC (high dose cytarabine) consolidation therapy. PleurX catheter was placed for recurrent large volume malignant effusions.
      DISCUSSION: Traditional chemotherapy for AML is the current standard of care for MS. This patient has currently achieved remission and the mass has markedly reduced in size along with no activity on PET scan. Due to the difficulty in detection and diagnosis of MS, PET scan remains an important diagnostic tool. Retrospective case studies have determined isolated MS bears a better prognosis than concomitant AML or relapse AML. Estimated 3 year progression free survival rates range from 20-40% across retrospective reviews.
      CONCLUSIONS: Prompt diagnosis of MS and initiation of therapy is of dire importance to improve outcomes. MS remains such a rare disease that large powered assessments of treatment outcomes are not available. Hematopoietic stem cell transplantation along with chemotherapy demonstrates longer event-free and overall survival than chemotherapy alone. Further studies determining prognosticating factors for MS survival and remission are still needed.
      REFERENCE #1: Wilson CS, Medeiros LJ. Extramedullary Manifestations of Myeloid Neoplasms. Am J Clin Pathol. 2015 Aug;144(2):219-39. doi: 10.1309/AJCPO58YWIBUBESX. PMID: 26185307.
      REFERENCE #2: Darko Antic, Ivo Elezovic, Natasa Milic, Nada Suvajdzic, Ana Vidovic, Maja Perunicic, Irena Djunic, Mirjana Mitrovic, Dragica Tomin. Is there a "gold" standard treatment for patients with isolated myeloid sarcoma? Biomedicine & Pharmacotherapy, Volume 67, Issue 1, 2013, Pages 72-77, ISSN 0753-3322, https://doi.org/10.1016/j.biopha.2012.10.014.
      REFERENCE #3: L. Max Almond, Maria Charalampakis, Samuel J. Ford, David Gourevitch, Anant Desai. Myeloid Sarcoma: Presentation, Diagnosis, and Treatment. Clinical Lymphoma, Myeloma and Leukemia. Volume 17, Issue 5, P263-267, May 1, 2017. https://doi.org/10.1016/j.clml.2017.02.027
      DISCLOSURES: No relevant relationships by Hannah Shine, source=Web Response