The contributions to this chapter by Dr. Matthew P. Frosch, Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston Massachusetts, and Dr. Robert Folberg in several previous editions of this book are gratefully acknowledged. The principal focus of this chapter is on diseases of the central nervous system (CNS). At the end, we briefly describe some important disorders of the eye, which is linked anatomically…

The contributions to this chapter by Dr. Peter Pytel, Department of Pathology, University of Chicago, in several previous editions of this book are gratefully acknowledged. The peripheral nerves and skeletal muscles permit purposeful movement and provide the brain with sensory information about our surroundings. Both the anatomic distribution of lesions and their associated signs and symptoms are helpful in classifying neuromuscular diseases. The following discussion of…

The contributions to this chapter by Dr. Andrew Horvai, Department of Pathology, University of California, San Francisco in the previous edition of this book are gratefully acknowledged. Bone Structure and Function of Bone Bone provides mechanical support for the body, transmits forces generated by muscles, protects viscera, provides a niche for blood cell progenitors, and is intimately involved in calcium and phosphate homeostasis. It is produced…

The contributions to this chapter by Dr. Anirban Maitra, Professor of Pathology and Translational Molecular Pathology, The University of Texas, MD Anderson Cancer Center, Houston, Texas, in several previous editions of this book are gratefully acknowledged. Endocrine organs (also called glands ) secrete hormones that act on other tissues to maintain the body’s metabolic homeostasis and to mediate responses to the metabolic demands of acute stresses.…

The contributions to this chapter by Dr. Lora Hedrick Ellenson, Department of Pathology, Memorial Sloan Kettering Cancer Center, New York City, New York, and Dr. Susan C. Lester, Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, in the previous edition of this book are gratefully acknowledged. We also appreciate Dr. Lester's assistance in the current edition. Vulva The vulva is the external…

Penis Malformations Among the most common malformations of the penis are those in which the distal urethral orifice is abnormally located, either on the ventral (hypospadias) or dorsal (epispadias) aspect of the penis. The anomalous orifice may be constricted, resulting in urinary tract obstruction and an increased risk for urinary tract infections. Hypospadias occurs in 1 in 300 live male births and may be associated with…

The contributions to this chapter by Dr. Anirban Maitra, University of Texas, MD Anderson Cancer Center, Houston, Texas, in previous editions of this book are gratefully acknowledged. The pancreas is a transversely oriented retroperitoneal organ extending from the so-called “C loop” of the duodenum to the hilum of the spleen. Although the pancreas does not have well-defined anatomic subdivisions, adjacent vessels and ligaments serve to demarcate…

Liver The contributions to this chapter by Dr. Neil D. Theise, Department of Pathology at NYU Grossman School of Medicine, New York, New York, and the late Dr. Nelson Fausto, Department of Pathology, University of Washington, Seattle, Washington, in previous editions of this book are gratefully acknowledged. The healthy adult liver weighs 1400 to 1600 gm. It has a dual blood supply, with the portal vein…

The contributions to this chapter by Dr. Jerrold R. Turner, Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts, in several previous editions of this book are gratefully acknowledged. The gastrointestinal tract is a hollow tube consisting of the esophagus, stomach, small intestine, colon, rectum, and anus. Each region has complementary, highly integrated functions that regulate the intake, processing, and absorption of ingested nutrients and the…

The contributions of Dr. Anthony Chang, Department of Pathology, University of Chicago, and Dr. Zoltan Laszik, Department of Pathology, University of California San Francisco, to previous editions of this chapter are gratefully acknowledged. The well-known quotation “What is man…but an ingenious machine for turning, with infinite artfulness, the wine of Shiraz into urine” gives rather dramatic importance to the renal apparatus. In reality, the kidney is…

The contributions to this chapter by Dr. Aliya Husain, Department of Pathology, University of Chicago, Chicago, Illinois, in several previous editions of this book are gratefully acknowledged. The major function of the lung is to provide the body with oxygen and to remove carbon dioxide. Efficient gas exchange is enabled by the lung’s anatomy, which serves to maximize the surface area of air spaces through which…

The hematopoietic and lymphoid systems are affected by a wide spectrum of diseases. One useful way to organize these disorders is based on whether they primarily affect red cells, white cells, or the coagulation system, which includes platelets and clotting factors. The most common red cell disorders are those that lead to anemia, a state of red cell deficiency. Clinically significant white cell disorders, by contrast,…

The heart is a truly remarkable organ, beating more than 40 million times per year and pumping over 7500 liters of blood a day; in a typical life span, its cumulative output would fill three supertankers. The cardiovascular system is the first organ system to become functional in utero (at approximately 8 weeks of gestation); without a beating heart and vascular supply, development cannot proceed, and the…

Vascular diseases are responsible for some of the most common and lethal conditions afflicting humans. Although most clinically significant disorders involve arterial lesions, venous pathologies can also wreak havoc. Two types of vascular lesions cause disease: Narrowing or complete obstruction of vessel lumina, occurring either progressively (e.g., by atherosclerosis) or acutely (e.g., by thrombosis or embolism) Weakening of vessel walls, causing dilation and/or rupture The contributions to this…

Most diseases are influenced by environmental factors, and some are directly caused by environmental insults. Broadly defined, the ambient environment encompasses the various outdoor, indoor, and occupational settings in which humans live and work. In each of these settings, the air people breathe, the food and water they consume, the toxic agents they are exposed to, and the stresses they encounter are major determinants of health.…

Cancer is the second leading cause of death in the United States; only cardiovascular diseases exact a higher toll. Cancer is not one disease but many, all sharing a profound dysregulation of growth. Some types of cancer are curable, while others are virtually always fatal. Advances in diagnosis, treatment, and prognosis will depend on a deeper understanding of the molecular and cellular basis of each type…

Immunity refers to protection against infections. The immune system is the collection of cells and molecules that are responsible for defending the body against the countless pathogens that individuals encounter. Defects in the immune system are the cause of immunodeficiency diseases, which render individuals easy prey to infections. But the immune system is itself capable of causing tissue injury and disease, called hypersensitivity disorders . This…

In this chapter we discuss genetic and pediatric diseases together, because many disorders of childhood are of genetic origin. However, it must be borne in mind that not all genetic disorders manifest in infancy and childhood, and, conversely, many pediatric diseases are not of genetic origin. To the latter category belong diseases resulting from immaturity of organ systems. The contributions of Dr. Anirban Maitra, Department of…

The health of cells and tissues depends on the circulation of blood, which delivers oxygen and nutrients and removes wastes generated by cellular metabolism. Under normal conditions, as blood passes through capillary beds, there is little net movement of water and electrolytes into the tissues (discussed later). This balance is often disturbed by pathologic conditions that alter endothelial function, increase vascular hydrostatic pressure, or decrease plasma protein…

Inflammation is a response of vascularized tissues to infections and tissue damage that brings cells and molecules of host defense from the circulation to the sites where they are needed, in order to eliminate the offending agents. Although in common medical and lay parlance inflammation suggests a harmful reaction, it is actually a protective response that is essential for survival. It serves to rid the host…