Can immunohistochemistry be wrong?
The most common causes of false-positive signals in IHC preparations include nonspecific background signal, endogenous peroxidase, the use of inappropriately high antibody concentrations, pigment mistaken for true signal, endogenous biotin, drying artifact, and “pseudospecific” signal.
What does negative for Melan A mean?
94 Melan A is a sensitive marker for benign and malignant adrenocortical neoplasms, and test results are generally negative in pheochromocytomas and extra-adrenal carcinomas, including renal cell carcinoma and hepatocellular carcinoma.
What is HMB-45 negative?
Abstract. Desmoplastic malignant melanoma (DMM) and spindle cell malignant melanoma (SCMM) form a continuum without a discrete separation. One feature characteristic of DMM is a negative reaction for HMB45, a marker for premelanosomes. Fifty-six cases of SCMM were stained with HMB45.
What is Melan A staining?
Melan-A, also known as MART-1, is an additional melanocytic marker and has proved to be useful in identifying metastatic tumors of melanocytic origin. The usefulness of this marker to discriminate pigmented actinic keratosis from early melanoma in situ, however, has not yet been a subject of investigation.
How accurate is immunohistochemistry?
In specimens for which pathologists rendered their final diagnosis with a single round of stains, both IHC and GEP exceeded 90% accuracy. However, when the diagnosis required a second round, IHC significantly underperformed GEP (67% to 83%, P < 0.001).
What does HMB-45 positive mean?
The presence of one or two isolated HMB-45–positive cells may pose diagnostic difficulty in differentiating isolated melanoma cells from melanophages and benign cells showing melanocytic differentiation, such as nevus cells in lymph nodes (19).
What is HMB-45 used for?
HMB-45 is a monoclonal antibody that reacts against an antigen present in melanocytic tumors such as melanomas, and stands for Human Melanoma Black. It is used in anatomic pathology as a marker for such tumors.
What does HMB 45 stain?
What does Melan-A positive mean?
The presence of Melan-A positive dermal cells in excisions for melanoma in situ represents a frequent conundrum for pathologists. These cells may represent superficially invasive melanoma, benign, incidental, dermal nevi or non-specific staining of dermal melanophages.
How do you interpret immunohistochemistry results?
The IHC test gives a score of 0 to 3+ that measures the amount of HER2 receptor protein on the surface of cells in a breast cancer tissue sample. If the score is 0 to 1+, it’s called “HER2 negative.” If the score is 2+, it’s called “borderline.” A score of 3+ is called “HER2 positive.”
How does immunohistochemistry detect tumor markers?
Immunohistochemistry is one of the techniques pathologists use when they examine samples of cancer tissue. This technique uses antibodies to make certain proteins in cells visible under a microscope. An antibody is a molecule that binds to another type of molecule.
How reliable is HMB-45 as a marker of melanoma?
Baisden et al. ( 1) considered HMB-45 to be a more reliable and specific marker of melanoma cells because of higher clarity and minimal background staining in lymph node biopsies.
What is the pathophysiology of HMB-45 positive cells?
HMB-45 correlates with melanosome production and thus a melanocytic origin of HMB-45-positive cells. HMB-45 may correlate best with factors that stimulate melanocytic proliferation and production of melanosomes.
What is HMB-45 immunohistochemical staining of sentinel lymph nodes?
HMB-45 immunohistochemical staining of sentinel lymph nodes. A specific method for enhancing detection of micrometastases in patients with melanoma. Am J Surg Pathol 2000; 24: 1140–1146.
Can HMB-45 stain S-100 cells?
The usage of S-100 staining, which is known to stain almost 100% of melanomas, partially compensates for the lower sensitivity of HMB-45. However, as S-100 expression is not melanocyte specific, an S-100–positive and HMB-45–negative cluster of cells can be doubtful.