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The occurrence of more than one distinct form of an organism in a single life cycle.



an environmentally produced change in the incidence of disease and causes of death as well as in the properties of individual diseases, that is, nosologic entities (see NOSOLOGY).

During the 20th century, extensive immunization of populations and nationwide preventive measures in economically developed countries have eradicated many infectious diseases, for example, plague and poliomyelitis, and have sharply reduced infant mortality caused by infectious diseases. Changes in living conditions have reduced the incidence of diseases that stem from nutritional deficiency, for example, avitaminoses and iron-deficiency anemia. On the other hand, the incidence of injuries, tumors, and cardiovascular and viral diseases has increased.

New hereditary and occupational diseases have resulted from such environmental changes as those that accompany the growth of the chemical industry. Therapy-induced pleomorphism is a change in the clinical picture of a disease as a result of treatment. For example, the use of drugs has led to the disappearance of severe forms of thyrotoxicosis and anemia. Similarly, tuberculous meningitis, comas in diabetes mellitus, and acute pulmonary suppuration have become rare. In leukemia, tumor cells have disappeared from bone marrow because of the use of cytostatic agents, but they multiply in the nervous system and viscera. Undesirable side effects may follow medicinal treatment, and beyond a certain intensity these constitute a drug disease. The aftereffects of gastric or cardiac surgery, for example, can also give rise to disease.

Diseases that have received a new nosologic classification because of the growth of medical knowledge should not be considered examples of pleomorphism.


Davydovskii, I. V. Patologicheskaia anatomiia i patogenez boleznei cheloveka, 3rd ed., vols. 1–2. Moscow, 1956–58.
Shul’tsev, G. P. “Terapevticheskii patomorfizm.” Klinicheskaia meditsina. 1973, no. 6.
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References in periodicals archive ?
A, Classical invasive lobular carcinoma and lobular carcinoma in situ of the breast are characterized by loosely cohesive cells displaying low cytologic atypia, absence of significant pleomorphism, and scant cytoplasm.
Pleomorphism and cellular atypia allow separation of ostesarcoma, chondrosarcoma, and carcinoma with giant cells from GCT.
2,8) Features that have been associated with local or distant recurrence include high cellularity, mitotic activity, nuclear pleomorphism, and necrosis.
22,23) Rife also found direct evidence of pleomorphism, the phenomenon of a bacterial pathogen having a corresponding viral form; and depending on the mixture of proteins that the bacterium digested, it could transform reversibly between its viral and bacterial forms.
The marked cellular pleomorphism of the melanoma from the cockatoo in this case, which warrants the description of an anaplastic malignant melanoma, is similar to other cases of avian malignant melanomas.
3,4) Histologically, these tumors show cellular pleomorphism, bizarre giant cells, hemorrhage, and necrosis.
On histopathological examination, a spindle cell tumour with nuclear pleomorphism was identified (Fig.
2,17,19) Atypical features, including increased mitotic activity, cytologic atypia with nuclear pleomorphism, prominent nucleoli, hyperchromasia, and necrosis, if observed, are usually associated with cases that either recurred or had a malignant clinical outcome (Figure 1, F).
Topics include pleomorphism, gut health and advanced Pleo-Sanum immuno-modulation, and Pleo-Sanum in autoimmune disease treatments.
1) The term "dedifferentiated" implies that a portion of cells from the chondrosarcoma have degenerated into a high-grade malignant form that is characterized by pleomorphism, anaplasia, hypercellularity, and increased mitoses.
The pathologic specimens were evaluated at our pathology department and the Johns Hopkins Pathology Department, and were reported as malignant EAML with pleomorphism, necrosis, and atypical mitotic figures (Fig.
However, other areas had much higher cellularity, with nuclear pleomorphism and scattered multinucleated giant cells.