Osteosarcoma in Children

 Musculoskeletal System, Oncology  No Responses »
Aug 312010
 

EPIDEMIOLOGY.

The annual incidence of osteosarcoma in the USA is 5.6 cases per million children <15 yr of age. The highest risk period for development of osteosarcoma is during the adolescent growth spurt, suggesting an association between rapid bone growth and malignant transformation. Patients with osteosarcoma are taller than their peers of similar age.

PATHOGENESIS.

Although the cause of osteosarcoma is unknown, certain genetic or acquired conditions predispose patients to development of osteosarcoma.

Patients with hereditary retinoblastoma have a significantly increased risk of developing osteosarcoma. The sites of osteosarcoma in these patients initially were thought to be located only in previously irradiated areas, but more recently they have been shown to arise in sites far from the radiation field. Predisposition to development of osteosarcoma in these patients may be related to loss of heterozygosity of the RB gene.

Osteosarcoma also occurs in the Li-Fraumeni syndrome, which is a familial cancer syndrome associated with germline mutations of the p53 gene.

The pathologic diagnosis of osteosarcoma is made by demonstration of a highly malignant, pleomorphic, spindle cell neoplasm associated with the formation of malignant osteoid and bone. Continue reading »

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An Introduction to Lipodystrophy

 Skin  No Responses »
Aug 312010
 
Several rare conditions are associated with loss of fatty tissue in a partial or generalized distribution.

Partial Lipodystrophy. Partial lipodystrophy may be familial or acquired. Loss of adipose tissue is not preceded by an inflammatory phase, and histopathologic examination reveals only absence of subcutaneous fat.

There are 3 forms of familial partial lipodystrophy (FPLD).

Type I (FPLD1-Kobberling) is characterized by loss of adipose tissue confined to the extremities and gluteal region. Fat distribution of the face, neck, and trunk may be normal or increased. Hyperlipidemia, insulin-resistant diabetes mellitus, and eruptive xanthomas may be seen. The gene is unknown, but only females are affected.
Type 2 (FPLD2-Dunnigan) is caused by mutations in the laminin A/C gene. Fat distribution is normal in childhood, but atrophy commences with puberty. Lipodystrophy is seen in the trunk, gluteal region, and extremities. Adipose tissue accumulates in the face and neck and may also be seen in the axillae, back, labia majora, and infra-abdominal region. Insulin-resistant diabetes mellitus and hypertriglyceridemia develop, but high-density lipoprotein and cholesterol levels are low. Both males and females are affected, but the diagnosis may be more difficult in males due to body habitus.
Type 3 (FPLD3) is caused by mutations in the peroxisome proliferation–activated receptor gamma (PPARG) gene. Lipodystrophy is seen in the limbs and gluteal region. Insulin-resistant diabetes mellitus, primary amenorrhea, acanthosis nigricans, hypertension, and fatty infiltration of the liver are present.

Acquired partial lipodystrophy (Barraquer-Simons syndrome) is rare. Females are more commonly affected. Fat loss begins in childhood or adolescence and affects the face, neck, arms, thorax, and upper abdomen. Excess fat is seen in the hips and legs, especially in females. Low levels of C3 are almost universally seen. C3 nephritic factor is also present. C3 nephritic factor stabilizes C3 convertase, allowing for unopposed activation of the alternate complement pathway Continue reading »

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Approach to Chronic Abdominal Pain in Children

 Gastroenterology  No Responses »
Aug 302010
 
Children with chronic abdominal pain account for 5% of all outpatient visits in the pediatric age group. Up to one-third of all children have this complaint, yet less than 10% of these children will have an identifiable organic etiology for their pain. These issues can have great impact on the functioning of the entire family, often causing work absence for the parents, excessive school absence for the child, and feelings of helplessness for the entire family unit.
Definition
Chronic abdominal pain is defined as at least 3 episodes occurring within a 3-month time-span that interferes with normal activity.
Incidence
It is slightly more common in girls than in boys, and usually occurs between the ages of 5 and 12 years. There is an increased incidence of recurrent abdominal pain in the families of these children.
History
The evaluation of a child with chronic abdominal complaints—or for that matter, any problem at all—starts with a comprehensive history. This should start with an interview of the child, as long as he is of the developmental stage in which he can respond to questions with verbal answers. Once exhausting the information available from the child, the parent or caretaker is interviewed. This allows the child to become part of the process, rather than Continue reading »
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