Porth's Essentials of Pathophysiology, 4e

131

Neoplasia

C h a p t e r 7

TABLE 7-1 Names of Selected Benign and Malignant Tumors According toTissueTypes TissueType BenignTumors MalignantTumors

Epithelial Surface Glandular Connective Fibrous

Papilloma Adenoma

Squamous cell carcinoma

Adenocarcinoma

Fibroma Lipoma

Fibrosarcoma Liposarcoma

Adipose Cartilage

Chondroma

Chondrosarcoma Osteosarcoma Hemangiosarcoma Lymphangiosarcoma

Bone

Osteoma

Blood vessels Lymph vessels Lymph tissue

Hemangioma Lymphangioma

Lymphosarcoma

Muscle Smooth Striated

Leiomyoma

Leiomyosarcoma

Rhabdomyoma

Rhabdomyosarcoma

Neural Tissue Nerve cell

Neuroma

Neuroblastoma

Glial tissue

Glioma

Glioblastoma, astrocytoma, medulloblastoma, oligodendroglioma

Nerve sheaths

Neurilemmoma

Neurilemmal sarcoma Meningeal sarcoma

Meninges

Meningioma

Hematologic Granulocytic Erythrocytic Plasma cells Lymphocytic

Myelocytic leukemia Erythrocytic leukemia Multiple myeloma

Lymphocytic leukemia or lymphoma

Monocytic

Monocytic leukemia

Endothelial Tissue Blood vessels

Hemangioma Lymphangioma

Hemangiosarcoma Lymphangiosarcoma

Lymph vessels

Benign Neoplasms Benign tumors are composed of well-differentiated cells that resemble the cells of the tissues of origin and are generally characterized by a slow, progressive rate of growth that may come to a standstill or regress. 2,3 For unknown reasons, benign tumors have lost the ability to suppress the genetic program for cell proliferation but have retained the program for normal cell differentiation.

They grow by expansion and remain localized to their site of origin and do not have the capacity to infiltrate, invade, or metastasize to distant sites. Because they expand slowly, they develop a surrounding rim of com- pressed connective tissue called a fibrous capsule . 3 The capsule is responsible for a sharp line of demarcation between the benign tumor and the adjacent tissues, a factor that facilitates surgical removal.

TABLE 7-2 Characteristics of Benign and Malignant Neoplasms Characteristics Benign

Malignant

Cell characteristics

Well-differentiated cells that resemble cells in the tissue of origin

Cells are undifferentiated, with anaplasia and atypical structure that often bears little resemblance to cells in the tissue of origin Variable and depends on level of differentiation; the more undifferentiated the cells, the more rapid the rate of growth Grows by invasion, sending out processes that infiltrate the surrounding tissues Gains access to blood and lymph channels to metastasize to other areas of the body

Rate of growth

Usually progressive and slow; may come to a standstill or regress

Mode of growth

Grows by expansion without invading the surrounding tissues; usually encapsulated

Metastasis

Does not spread by metastasis