28 March 2022: Textbook Updates

We have posted updates of the following topics:

Chemistry, toxicology & urinalysis > General chemistry > Metabolism > Lipid panel
by Archana Shetty, M.B.B.S., M.D.
Topic summary: Set of chemistry tests to measure the level of various fats in a person’s blood. Typical lipid profile includes testing for total cholesterol, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglycerides (TG), very low density lipoprotein cholesterol (VLDL-C) and non-HDL cholesterol. Known risk factors for developing heart disease include cigarette smoking, history of heart disease or atherosclerosis, history of stroke or heart attack. As a part of routine health check up, a fasting or nonfasting lipoprotein profile should be obtained at least every 5 years in all adults.

Cytopathology > Effusion cytology > IHC panels
by Lawrence Hsu Lin, M.D., Ph.D., Tamar C. Brandler, M.D., M.S.
Topic summary: Serous cavities can be involved by metastatic neoplasms, inflammatory / infectious conditions or primary malignancies. Clinical and radiological correlation with cytomorphology is vital to tailor an appropriate immunostain panel. Use of immunostaining panel with multiple stains is beneficial since no single stain has 100% sensitivity or specificity. Positive stains are more useful than negative stains since a larger percentage of cases in effusion can lose expression as compared with primary tumors.

Molecular markers > KRAS
by Yi Ding, M.D., Ph.D.
Topic summary: Kirsten RAt Sarcoma virus (KRAS) gene on chromosome 12p12.1. KRAS is part of the RAS / MAPK pathway and plays critical roles in cell growth, proliferation and differentiation. KRAS is one of the most frequently mutated oncogenes in human malignancies. KRAS mutation in lung cancer generally conveys a poor prognosis and resistance to EGFR tyrosine kinase inhibitor therapy. KRAS mutations are usually detected by molecular technology, including PCR, Sanger sequencing and next generation sequencing (NGS).

Skin nontumor > Lichenoid and interface reaction patterns > Pityriasis lichenoides chronica
by Gülçin (Güler) Şimşek, M.D.
Topic summary: Cutaneous eruption, papulosquamous, necrotic or mixed lesions. Asymptomatic red-brown and small sized papulosquamous lesions arise in crops and usually involve trunk, upper extremities and buttocks. Commonly affects children and young adults with equal sex ratios (slightly more common in males). Relapsing and remitting course persists for months or a few years. Treatment: topical steroids; topical immunomodulators (tacrolimus, pimecrolimus); oral antibiotics (erythromycin, tetracycline such as doxycycline); phototherapy; systemic steroids.

Stains & CD markers > Colon cancer biomarker testing (including MSI / Lynch)
by Saba Shafi, M.D., Wei Chen, M.D., Ph.D.
Topic summary: Colon cancer biomarker testing is essential for screening for Lynch syndrome, therapeutic and prognostic predictions in advanced colorectal cancer (CRC) and identification of other hereditary polyposis / cancer syndrome in indicated patients. Lifetime risk of colorectal and endometrial cancers in Lynch syndrome as high as 50% and 60%, respectively. Lynch syndrome patients have a germline mutation affecting an MMR gene; subsequently, an additional somatic mutation or deletion must be acquired in the other allele of the gene (with the germline mutation) for MMR deficiency to manifest. Patients with MMR deficient colorectal cancer have a better prognosis than those with stage matched MMR proficient colorectal cancer.

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