{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Myoglobin is a single-chain globular protein of 153 amino acids, containing a heme (iron-containing porphyrin) prosthetic group in the center around which the remaining apoprotein folds. With a molecular weight of 16.7 kDa, it is the primary oxygen-carrying pigment of muscle tissues. Immunostaining with Myoglobin provides a specific, sensitive and practical procedure for the identification of Rhabdomyosarcoma. Since myoglobin is found exclusively in skeletal and cardiac muscle and is not present in any other cells of the human body, it may be used to distinguish Rhabdomyosarcoma from other soft-tissue tumors. Myoglobin staining is also useful when demonstrating rhabdomyoblastic differentiation in other tumors, e.g., Neurogenic Sarcomas and Malignant Mixed Mesodermal Tumors of the uterus and ovary."}]}]}