We have posted updates of the following topics:Prostate gland & seminal vesicles > Immunohistochemistry
by Brian Ma, M.D., Guang-Qian Xiao, M.D., Ph.D.
Topic summary: Diagnostic biomarker study of prostate tissue is one of the most common applications of immunohistochemistry in surgical pathology, especially for prostate needle biopsies. Most used immunohistochemical stains include basal cell markers and prostate specific markers. Pathophysiology involves survival and growth of normal and prostate cancer cells relying on the constitutive expression of AR and its signaling. For primary atypical prostatic glands: IHCs reveal atypical prostatic glands negative for p63 and 34 beta E12 (absence of basal cells) and positive for AMACR / p504s, supporting the diagnosis of prostatic adenocarcinoma.
Soft tissue > Fibroblastic / myofibroblastic > Superficial CD34+ fibroblastic tumor
by Borislav A. Alexiev, M.D.
Topic summary: Distinctive low grade neoplasm of the skin and subcutis, characterized by a fascicular proliferation of spindled cells with abundant, eosinophilic, granular to glassy cytoplasm, marked nuclear pleomorphism and low mitotic count. Most tumors occurred in middle aged adults (median age 38 years, range 20 – 76 years) with slight male predominance. May occur anywhere in the body but most lesions appear on the lower limbs, particularly the thighs.
Soft tissue > General > Histology-skeletal muscle
by Norbert Sule, M.D., Ph.D.
Topic summary: Specialized contractile tissue responsible for the voluntary movements. Normal skeletal muscle is formed from the primitive mesenchymal element of the paraxial mesoderm (somite) which divides into ventral dorsolateral somite or dermatomyotome. Contraction of skeletal muscle is controlled by large motor nerve fibers of the alpha neuron located in the anterior horn of the spinal cord and motor nuclei of the brain. Only a few residual satellite myoblasts are present in the mature muscle that are able to play a role in the repair and regeneration.
Soft tissue > Uncertain differentiation > CIC-DUX4 fusion tumor
by Borislav A. Alexiev, M.D., Lawrence J. Jennings, M.D., Ph.D.
Topic summary: Undifferentiated round cell sarcoma with capicua-double homeobox 4 (CIC-DUX4) gene fusion. Aggressive sarcoma arising predominantly in soft tissues of children and young adults. MYC amplification in majority of cases. Metastatic disease may be present at initial presentation. Tissue sampling is the gold standard for a definitive diagnosis. Patients treated with neoadjuvant chemotherapy showed an inferior survival compared to patients managed by surgery first.
Stains & molecular markers > SMAD4 / DPC4
by Xiaoyan Liao, M.D., Ph.D., Dongwei Zhang, M.D., Ph.D.
Topic summary: One of the SMAD family of transcription factor proteins, encoded by SMAD4 gene located on chromosome 18q21.1. Immunohistochemical staining for SMAD4 showing loss of nuclear stain is practically a surrogate for SMAD4 genetic mutation. Once in the nucleus, the complex of SMAD4 and 2 R-SMADs binds to DNA and regulates the expression of different genes depending on the cellular context. Nuclear stain if SMAD4 protein intact. Loss of SMAD4 nuclear expression combining with other immunomarkers can be used to determine tumor origin in cases of metastasis of unknown primary.