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Marfan Syndrome

Etiology Marfan syndrome (MFS) is an autosomal dominant disorder. Prevalence and Epidemiology The incidence in the general population is estimated at 1 in 5000 to 10,000. The majority of patients will have familial incidence, although approximately one third of cases occur sporadically, representing de novo mutations. Clinical Presentation MFS is a disorder of connective tissue, involving the cardiovascular, ocular, and skeletal systems, as well as the…

Osteogenesis Imperfecta

Osteogenesis imperfecta (OI), also known as brittle bone disease or Lobstein syndrome, is a common heritable disorder of collagen synthesis that results in defective, weak bony matrix, leading to bone fragility with fractures and deformity. A wide range of clinical manifestations may be seen, ranging from perinatal death to premature osteoporosis presenting in middle-aged adults. Important secondary clinical features are growth impairment resulting in a rhizomelic…

Storage Diseases

Lysosomal storage diseases are a group of inborn errors of metabolic disorders characterized by accumulation of incompletely metabolized substrates inside lysosomes due to deficiency in one of the numerous enzymes required for substrate degradation. They comprise more than 30 different syndromes and are generally divided into lipidoses, glycogenoses, and mucopolysaccharidoses (MPS). Most of these disorders are severely debilitating and lead to premature death. The focus of…

Gaucher Disease

Etiology Gaucher disease bears the name of Philippe Gaucher, a French dermatologist who first described the clinical syndrome. Understanding of the condition was greatly enhanced in 1965 when it was recognized that the disease was due to a functional deficiency of the enzyme β-glucosidase. This deficiency results in the accumulation of glucosylceramide, a cell membrane metabolite, in lysosomes of cells of the monocyte/macrophage lineage. Prevalence and…

Pituitary and Thyroid Disorders

Acromegaly and Pituitary Gigantism Etiology Acromegaly and pituitary gigantism are conditions resulting from hypersecretion of the growth hormone (GH) from the pituitary gland. The onset of GH hypersecretion in adults after the growth plates have fused results in acromegaly. The onset of GH hypersecretion in children and adolescents before fusion of the growth plates results in pituitary gigantism. The most common cause of GH hypersecretion is…

Amyloidosis

Etiology Amyloidosis comprises a heterogeneous group of diseases in which otherwise normal proteins acquire alternative misfolded states and form insoluble fibrils termed amyloid fibrils. Subsequently, extracellular deposition of amyloid fibrils into various organs and tissues results in infiltration, swelling, and progressive loss of function of the affected organ. It was the description of the autopsy of a young man back in 1639 by a Dutch physician,…

Hyperparathyroidism, Renal Osteodystrophy, Osteomalacia, and Rickets

Hyperparathyroidism Etiology A review of more than 20,000 cases of primary hyperparathyroidism found that, in 89% of patients, the cause was a solitary adenoma in the parathyroid gland and that 10% had multiglandular hyperplasia. Parathyroid carcinoma and cysts causing primary hyperparathyroidism are very unusual, occurring in less than 1% of cases. Prevalence and Epidemiology In the United States, primary hyperparathyroidism is said to affect 10 to…

Osteoporosis

Metabolic disorders of the skeleton affect bone as a tissue, so that all bones are involved histologically, although radiologic features are not always evident. Such diseases can be caused by genetic, endocrine, nutritional, or biochemical disorders. Osteoporosis is the most common metabolic bone disease. It is a quantitative abnormality of bone (“too little bone”), in contrast to rickets and osteomalacia, which are qualitative abnormalities of bone…

Myelofibrosis

Etiology Myelofibrosis is a chronic myeloproliferative disorder characterized by bone marrow fibrosis and the development of extramedullary hematopoiesis. Myelofibrosis can occur as a primary disease entity (also termed idiopathic myelofibrosis or agnogenic myeloid metaplasia ) or can occur secondary to diffuse bony metastatic disease, infections (e.g., tuberculosis and fungal infections), sarcoidosis, myeloma, and lymphoma. The etiology of primary myelofibrosis is unknown, but an increased incidence of…

Thalassemia

Etiology In 1925, Cooley and Lee described a series of patients suffering from severe anemia associated with splenomegaly and bone abnormalities. The name thalassemia , after fusion of the Greek words thalassa meaning “sea” and aima meaning “blood,” underlined the Mediterranean origin of the patients who were first described. Thalassemia is not a single disease but rather a group of diseases related to an inherited abnormality…

Sickle Cell Anemia

Etiology Sickle cell anemia, first described in a 20-year-old dental student from Grenada by Herrick in 1910, is the most common single-gene disorder in African Americans. Dr. Linus Pauling and his team identified the cause of SCA as a single substitution in the gene encoding of the β-hemoglobin (Hb) chain (valine substituted for glutamic acid). An individual with two abnormal chromosomes was designated as Hb SS…

Hemophilia and Related Disorders

Etiology Of all causes of hemophilia, types A and B are most associated with intraosseous and intraarticular bleeding. Hemophilia A (classic hemophilia) results from a deficiency of factor VIII. Hemophilia B (Christmas disease) is due to a functional deficiency of plasma thromboplastin component (factor IX). These disorders are both X linked and, therefore, manifest clinically in men but are carried by women. Prevalence and Epidemiology Classic…

Ischemic Bone Lesions

Ischemic bone lesions cover a wide spectrum of conditions with variable clinical and imaging findings in which oxygen delivery to the bone and marrow cells is impaired at least to some degree. Epiphyseal ischemic lesions have been more extensively investigated because of their clinical importance. MRI has definitely contributed to the detection and in-depth knowledge of the natural history of epiphyseal osteonecrosis. Etiology Ischemic bone lesions…

General Principles of MRI of the Bone Marrow

This chapter addresses general concepts on MRI of the bone marrow, with emphasis on common normal and abnormal marrow patterns. MRI plays a key role in marrow imaging because of its high sensitivity for detecting focal or diffuse alterations in marrow content. MRI of the bone marrow is also performed for other purposes, including medullary lesion characterization, disease staging, prognosis, and monitoring of treatment response. MRI…

Atypical Infections

Mycobacterial Infection In the 1950s, the atypical mycobacteria were recognized as human pathogens. They are morphologically similar to Mycobacterium tuberculosis but have different colonial characteristics. Because there is no evidence of human-to-human transmission, the atypical mycobacteria do not pose public health hazards. Etiology The mycobacterial organisms known to cause musculoskeletal system infections in humans are M. avium intracellulare–M. avium complex (found in soil, water, swine, cattle,…

HIV Infection and AIDS

Human immunodeficiency virus (HIV) infection is almost universally fatal if left untreated, leading to and being the etiologic agent of the acquired immunodeficiency syndrome (AIDS). The HIV epidemic is prevalent worldwide and is constantly evolving, being influenced by geographic, socioeconomic, and antiretroviral treatment–related factors. The Centers for Disease Control and Prevention (CDC) has published the current case definition criteria, which include three different categories of clinical…

Pediatric Infections

Introduction Musculoskeletal infections in children are relatively common occurrences. However, in the pediatric population, such infections may produce nonspecific clinical signs and symptoms and can occur in the absence of clinically apparent features, such as swelling and erythema. This diagnostic challenge is further compounded by the potential inability for a young child to assist in localizing a symptomatic region. Prompt recognition of bone and joint infectious…

Diabetic Pedal Infection

Introduction Etiology Although hematogenous spread is the most common cause of osteomyelitis in most other areas of the body, contiguous spread and direct implantation are the most common in the foot and ankle. Direct implantation can occur from puncture wounds or deep lacerations, open fractures, and surgery or injection procedures. The vast majority of osteomyelitis involving the foot and ankle in diabetic patients, however, occurs through…

Spinal Infection

Spinal Infection Etiology Spinal infection is a multicausal disease. The three most common are hematogenous spread, direct spread, and direct inoculation, which is usually iatrogenic. Arterial hematogenous spread can be due to an infectious focus anywhere in the body. This can be responsible for pyogenic and nonpyogenic infections and is the most common source of infection. It was previously believed that hematogenous spread can occur through…

Appendicular Infection

Osteomyelitis is infection of bone or bone marrow. It is usually caused by bacterial infection, less frequently by viruses and fungi and, rarely, parasites. It is subdivided into acute, subacute, and chronic stages, depending on the clinical presentation, which, in essence, reflects the interaction between the causative organism and the host's response ( Fig. 65-1 ). Despite the tremendous advancement in the imaging of bone infection,…