Dysplasia (from Greek, roughly: "bad form") is a term used in pathology to refer to an abnormality in maturation of cells within a tissue.
This generally consists of an expansion of immature cells, with a corresponding decrease in the number and location of mature cells.
Dysplasia is often indicative of an early neoplastic process.
The term dysplasia is typically used when the cellular abnormality is restricted to the originating tissue, as in the case of an early, in-situ neoplasm.
For example, epithelial dysplasia of the cervix (cervical intraepithelial neoplasia - a disorder commonly detected by an abnormal pap smear) consists of an increased population of immature (basal-like) cells which are restricted to the mucosal surface, and have not invaded through the basement membrane to the deeper soft tissues.
Myelodysplastic syndromes, or dysplasia of blood-forming cells, show increased numbers of immature cells in the bone marrow, and a decrease in mature, functional cells in the blood.
Dysplasia, in which cell maturation and differentiation are delayed, can be contrasted with metaplasia, in which cells of one mature, differentiated type are replaced by cells of another mature, differentiated type.
Skeletal dysplasias are a heterogeneous group of congenital anomalies which affect cartilage and/or bone growth.
There are many specific syndromes which are often very precisely characterised, down to knowledge of the specific gene defect in many cases, with only subtle differences between classifications.
Individually these syndromes have a low birth prevalence.
Skeletal dysplasias are generally caused by a single gene defect and most are autosomal recessive, however some types are autosomal dominant (e.g. achondroplasia) or caused by teratogens (e.g. warfarin).
The syndromes in this group have certain features in common, and allow for a general overview of these conditions.
The long bones of the limbs and the ribs are the structures most often affected, and many of the syndromes in this group have additional features which help to make the diagnosis.
The shortening of the long bones may primarily affect the proximal bones (the femur and humerus), called rhizomelic shortening or primarily affect the distal bones (the tibia/fibula and radius/ulna), called mesomelic.
The long bones may be curved or so weak that multiple fractures occur, leading to angulation within the long bones.
Radiographs of 45 wrists of 23 patients who had chondroectodermal dysplasia (CED) showed variable wrist malformations, which we grouped into eight categories.
In each patient, the wrists tended to be similar but seldom identical; in six patients they were sufficiently dissimilar that we classified the malformations in their two wrists into separate categories.
A ninth carpal bone was present in the wrists of all patients who were five years old or older (42 of 45 wrists).
It was located in the distal row, medial to the hamate bone and proximal to the fifth and sixth metacarpals.
A tenth carpal bone was found in six wrists.
Unlike the ninth carpal bone, it varied in location.
All of the carpal bones were deformed, and two or three separate ossification centers of the hamate were found in some individuals.
Fusions between the capitate, the hamate, and the ninth carpal bone were present by the last available examination in 71% of the 45 hands: these included fusions between the capitate and hamate in 7%, between the hamate and the ninth carpal bone in 47%, and between all three bones in 18%.
Re:What Is Low-Grade Dysplasia/Dysplasia?: - 2007/10/28 20:29What Is Low-Grade Dysplasia/Dysplasia?: Skeletal Dysplasias: Diagnosis of skeletal dysplasia by multidisciplinary assessment: a report of two cases of thanatophoric dysplasia:
Skeletal dysplasias (also known as bone dysplasias, osteo-, osteochondro- or chondrodysplasias, or dysostoses) are genetic conditions affecting growth and development of the skeleton.
There is a great number of different conditions (see Nosology).
The clinical consequences may range from mild shortness without other complications to severely reduced stature ("dwarfism") with bone deformity and dysproportion between segments of the body.
Because skeletal dysplasias often present as short stature, the differential diagnosis must be made with other childhood disorders that may cause short stature, such as endocrine, intestinal or renal disorders.
Although reduced stature or bone deformity may be most evident to the eye, other organs or tissues (such as the nervous system, the inner ear, the eye, the joints, the muscles, the liver, the kidney, or the immune system, just to name some) can be affected in individuals with skeletal dysplasias, depending on what the precise diagnosis is.
Obtaining an accurate diagnosis is important for management as well as for genetic counseling.
Even if for most conditions the possibilities for treatment are limited, many complications can be avoided, or their onset delayed, by means of physical therapy, orthopedics, or surgery.
Health supervision by a physician knowledgeable of skeletal dysplasias, and who may refer to the appropriate specialist, is important.
Counseling on the psychological and social aspects related to short stature is also helpful.
Since most skeletal dysplasias are recognized at birth or during childhood, the relevant expertise is usually found in Pediatrics and Genetics centers.
