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CD45 IHC Test: Leukocyte Common Antigen, Lymphoma Marker, and Tumor Origin

Understand CD45 (leukocyte common antigen) IHC, what positive or negative staining means, how it helps identify lymphoma, and why marker panels are essential.

CD45 immunohistochemistry (IHC), also called leukocyte common antigen or LCA staining, detects a protein expressed on most nucleated blood and immune cells. Pathologists use...

CD56 IHC Test: Neuroendocrine Tumor, NK Cell Tumor, and Positive Staining

Learn what CD56 IHC positivity means in neuroendocrine tumors and NK-cell neoplasms, including staining patterns, marker panels, diagnostic pitfalls, and next steps.

CD56 immunohistochemistry (IHC) detects neural cell adhesion molecule (NCAM) in tissue. Pathologists most often use CD56 as part of a panel for neuroendocrine tumors...

CD117 (c-KIT) IHC Test: GIST, Mast Cell Tumors, Positive Staining, and Meaning

Understand what CD117 (c-KIT) IHC positivity means in GIST, mast cell disorders, leukemia, and other tumors, including staining patterns and follow-up tests.

CD117 immunohistochemistry (IHC) is a tissue stain that detects the KIT receptor protein on or within cells. Pathologists use it most often when evaluating...

CDX2 IHC Test: Colorectal Cancer Marker, GI Tumor Origin, and Positive Staining

Understand CDX2 IHC positivity in colorectal and GI cancers, including nuclear staining, metastatic tumor-origin panels, CDX2-negative colorectal cancer, and key pitfalls.

CDX2 immunohistochemistry (IHC) detects a nuclear transcription factor involved in intestinal epithelial differentiation. Pathologists use it most often to support gastrointestinal—especially colorectal—origin in an...

Chromogranin IHC Test: Neuroendocrine Tumor Marker, Positive Staining, and Tumor Differentiation

Understand chromogranin IHC positivity in neuroendocrine tumors, including granular staining, tumor differentiation, marker panels, negative results, and diagnostic pitfalls.

Chromogranin immunohistochemistry (IHC) detects proteins found in neurosecretory granules and is one of the classic tissue markers used to confirm neuroendocrine differentiation. Pathologists most...

Cyclin D1 IHC Test: Mantle Cell Lymphoma Marker, Positive Staining, and Diagnosis

Learn how cyclin D1 IHC supports mantle cell lymphoma diagnosis, what nuclear positivity means, why rare MCL can be negative, and which confirmatory tests are used.

Cyclin D1 immunohistochemistry (IHC) detects a cell-cycle protein that is strongly associated with mantle cell lymphoma (MCL) when it is abnormally expressed in B...

Cytokeratin 7 (CK7) IHC Test: Tumor Origin, Positive Staining Pattern, and Cancer Type

Learn what CK7 IHC positivity means, which cancers are often CK7 positive or negative, how CK7/CK20 patterns guide tumor origin, and where pitfalls occur.

Cytokeratin 7 (CK7) immunohistochemistry (IHC) detects keratin 7, a structural protein expressed by many glandular and transitional epithelia. Pathologists use CK7 primarily to help...

Cytokeratin 20 (CK20) IHC Test: GI Cancer, Bladder Cancer, Tumor Origin, and Staining Pattern

Understand CK20 IHC in colorectal, GI, bladder, and metastatic cancer, including CK7/CK20 patterns, positive staining, common pitfalls, and site-of-origin testing.

Cytokeratin 20 (CK20) immunohistochemistry (IHC) detects keratin 20, an intermediate-filament protein normally expressed by selected epithelial cells, especially in the lower gastrointestinal tract and...

D2-40 IHC Test: Mesothelioma, Lymphatic Tumor Marker, and Positive Staining

Understand D2-40 IHC in mesothelioma and lymphatic pathology, including membranous positivity, reactive mesothelial staining, marker panels, BAP1/MTAP, and pitfalls.

D2-40 immunohistochemistry (IHC) is an antibody stain that detects podoplanin, a cell-surface glycoprotein expressed by lymphatic endothelial cells, mesothelial cells, and several tumors. Pathologists...

Desmin IHC Test: Muscle Tumor Marker, Sarcoma Classification, and Positive Staining

Learn how desmin IHC staining helps identify muscle differentiation, classify smooth-muscle and skeletal-muscle tumors, and guide sarcoma diagnosis.

Desmin immunohistochemistry (IHC) is a tissue stain that helps pathologists identify muscle differentiation in a tumor. Desmin is an intermediate-filament protein normally found in...

DOG1 IHC Test: Gastrointestinal Stromal Tumor Marker, GIST Diagnosis, and Positive Staining

DOG1 IHC helps diagnose gastrointestinal stromal tumors. Learn what positive staining means, how it compares with KIT, and when molecular testing is needed.

DOG1 immunohistochemistry is mainly used to help identify gastrointestinal stromal tumors (GISTs), especially when the tumor’s shape and location suggest GIST but other stains...

DPC4 IHC Test: Pancreatic Cancer, SMAD4 Loss, and IHC Interpretation

DPC4/SMAD4 IHC helps evaluate pancreatic cancer by showing retained or lost SMAD4 protein. Learn what SMAD4 loss means, how the stain is interpreted, and why other tests are still needed.

DPC4 immunohistochemistry is a tissue test that shows whether tumor cells retain or lose SMAD4 protein, a tumor-suppressor protein frequently altered in pancreatic ductal...

Estrogen Receptor (ER) IHC Test: Breast Cancer Hormone Receptor Status and Positive Score

Estrogen receptor IHC measures ER protein in breast cancer. Learn the 1% positive cutoff, what ER Low Positive at 1%–10% means, how results are scored, and how ER status guides hormone therapy.

Estrogen receptor (ER) immunohistochemistry is the standard tissue test used to determine whether a breast cancer expresses estrogen receptors and may benefit from endocrine...

GATA3 IHC Test: Breast Cancer, Urothelial Cancer, Tumor Origin, and Positive Staining

GATA3 IHC helps identify breast and urothelial tumor differentiation. Learn what positive nuclear staining means and how pathologists assess tumor origin.

GATA3 immunohistochemistry is a tissue stain that helps pathologists identify breast and urothelial differentiation and narrow the likely origin of a carcinoma. GATA3 is...

Glypican-3 IHC Test: Liver Cancer Marker, Positive Staining, and HCC Meaning

Glypican-3 IHC can support hepatocellular carcinoma diagnosis. Learn what positive GPC3 staining means and how it fits with other liver tumor markers.

Glypican-3 (GPC3) immunohistochemistry is a tissue stain used mainly to support the diagnosis of hepatocellular carcinoma (HCC), particularly when a liver tumor must be...

HepPar-1 IHC Test: Hepatocellular Carcinoma Marker, Liver Tumor Origin, and Staining Meaning

HepPar-1 IHC supports hepatocellular differentiation. Learn what granular cytoplasmic staining means and how the marker helps evaluate possible HCC.

HepPar-1 immunohistochemistry is a tissue stain used to show hepatocellular differentiation and support the diagnosis of hepatocellular carcinoma (HCC). The antibody recognizes a mitochondrial...

HER2 IHC Test: Breast Cancer, Gastric Cancer, Protein Expression Score, and HER2 Status

HER2 IHC scores tumor protein expression in breast and gastric cancer. Learn what 0, 1+, 2+, and 3+ mean, when ISH is needed, how gastric scoring differs, and why HER2-low matters.

HER2 immunohistochemistry (IHC) measures HER2 protein expression on tumor-cell membranes and helps determine whether a cancer may qualify for HER2-directed therapy. It is used...

HMB-45 IHC Test: Melanoma Marker, Positive Staining, and Melanocytic Tumor Meaning

Learn what HMB-45 IHC positivity means, how the melanoma marker is interpreted with S100, SOX10, and Melan-A, and why staining alone is not diagnostic.

HMB-45 immunohistochemistry (IHC) is a tissue stain used to identify melanocytic differentiation in tumors and skin lesions. The antibody recognizes a melanosome-associated protein related...

INSM1 IHC Test: Neuroendocrine Tumor Marker, Nuclear Staining, and Diagnostic Meaning

Learn how INSM1 IHC nuclear staining identifies neuroendocrine differentiation, how it compares with synaptophysin and chromogranin, and what positive results mean.

INSM1 immunohistochemistry (IHC) is a tissue stain that helps pathologists identify neuroendocrine differentiation in tumors. INSM1 is a transcription factor involved in neuroendocrine development,...

Ki-67 IHC Test: Tumor Proliferation Index, High Score, and Prognosis Meaning

The Ki-67 IHC test measures tumor-cell proliferation. Learn what a high Ki-67 score means, how the index is counted, tumor-specific cutoffs, prognosis, and key limitations.

Ki-67 immunohistochemistry (IHC) estimates how actively tumor cells are dividing. A pathologist stains a tissue sample for Ki-67, a protein found in proliferating cells,...