Isolated myeloid sarcoma (MS) is a rare extramedullary presentation of acute myeloid leukemia (AML). Little is known about MS outcomes due to its rarity. A population-based analysis of MS using the Survival, Epidemiology, and End Results (SEER) database was performed. We identified 345 patients, aged 15 or older, diagnosed with isolated MS between 1973 and 2010. Overall survival (OS) was calculated and compared between MS and non-MS AML using the log-rank test. Survival was also evaluated based upon the primary site of disease presentation. The 3-year survival rate for MS (0.319; 95% confidence interval [CI]: 0.267-0.371) was greater than for non-MS AML (0.172; 95% CI: 0.168-0.175). There was variation in survival based on the site of involvement. The survival rates for isolated MS involving the pelvis/genitourinary organs, eyes/gonads and gastrointestinal mucosa appeared to be slightly improved when compared to primary sites of soft tissues, lymphatic/hematopoietic tissues or nervous system.

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A 25-year-old, previously healthy female presented with pleuritic chest pain, dyspnea, and dry cough. Auscultation of the lungs demonstrated an absence of breath sounds on the left. Imaging with computed tomography (CT) and positron emission tomography (PET) modalities confirmed a large pleural effusion, but also revealed an anterior PET-avid mediastinal mass, measuring 11.2 cm by 6.0 cm, with a small pericardial effusion. There was also near-complete opacification of the left lung and a rightward mediastinal shift with displacement of adjacent structures.She was hospitalized and underwent placement of a left pleural chest tube. The pleural fluid was exudative and cellular, consisting of 12% atypical lymphoid cells expressing cytoplasmic CD3, CD7, CD34, but not surface CD3 or TdT. She then underwent a biopsy of a left internal mammary node, with pathological evaluation confirming a diagnosis of T-cell acute lymphoblastic lymphoma (Image 1A). Cytogenetic analysis revealed multiple abnormalities including a chromosome 17p deletion (Image 1B), which was confirmed by interphase fluorescence in situ hybridization (FISH) demonstrating p53 deletion in 88% of nuclei (Image 1C). An immunostain for p53 showed positive staining in approximately 2% of tumor Image 1. Pathologic and cytogenetic findings of mediastinal mass biopsy. The specimen is composed of a diffuse infiltrate of medium-sized atypical lymphoid cells with oval nuclei, dispersed chromatin, occasional small nucleoli, and scant cytoplasm (A, H&E, 31000). Frequent mitotic figures are seen (arrows). Cytogenetic abnormalities revealed multiple abnormalities with the dominant clone showing the following abnormal karyotype, including a deletion involving the short arm of chromosome 17 (B, arrow): 47,XX,14,114,del(17)(p1?3),220[cp7]. A separate related minor clone was also present: 89 91<4n>,idem,2X,2X,der(15)t(7;15)(q11.2;p11.2)32, 221 [cp3]. FISH analysis using a probe specific for the region containing TP53 on chromosome 17p confirmed TP53 loss in 44 of 50 interphase nuclei (C). An immunohistochemical stain for p53 revealed strong positive staining in approximately 2% of tumor cell nuclei (D, 3400).