Pathology Report Glossary: 100+ Medical Terms Explained

”

According to the College of American Pathologists, understanding the terminology in your pathology report is one of the most important steps you can take to become an active participant in your healthcare decisions. This comprehensive glossary explains over 100 common pathology terms in plain language.

This glossary is organized into categories to help you quickly find the terms you're looking for:

• Quick Reference: Terms are listed alphabetically within each category
• Plain Language Definitions: Medical jargon is explained in simple terms
• Context Notes: Learn what each term means for your specific situation
• Cross-References: Related terms are linked for deeper understanding

”

Pro Tip: Use your browser's Find function (Ctrl+F or Command+F) to quickly search for specific terms.

These terms describe the pathologist's conclusion about your tissue sample.

Benign

Definition: Non-cancerous. Benign cells and tumors are not cancer and do not spread to other parts of the body.

What it means: This is the best possible outcome. No cancer was found. Examples include fibroadenomas, lipomas, and many polyps.

Malignant

Definition: Cancerous. Malignant cells are cancer and have the potential to spread to other parts of the body.

What it means: Cancer is present. The specific type of cancer will be named (e.g., "invasive ductal carcinoma"). Additional tests and treatment planning will be needed.

Atypical / Atypia

Definition: Abnormal cells that aren't clearly benign or malignant. They look unusual but don't meet all the criteria for cancer.

What it means: The cells are concerning but not definitely cancer. This is often a "watchful waiting" situation. More monitoring, additional testing, or a repeat biopsy may be recommended.

Hyperplasia

Definition: An increase in the number of normal-looking cells in a tissue or organ.

What it means: More cells than normal, but they appear healthy. Usually benign, though some types (especially with atypia) may need monitoring.

Dysplasia

Definition: Abnormal development and growth of cells. The cells look abnormal but are not yet cancer.

What it means: Precancerous changes are present. Dysplasia is often graded as mild, moderate, or severe. Monitoring or treatment may be needed to prevent progression to cancer.

Carcinoma

Definition: A type of cancer that begins in the skin or in tissues that line or cover internal organs (epithelial tissue).

What it means: The most common type of cancer. Examples include squamous cell carcinoma, adenocarcinoma, and basal cell carcinoma.

Sarcoma

Definition: A type of cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective tissue.

What it means: A less common type of cancer that arises from mesenchymal cells. Examples include osteosarcoma (bone) and liposarcoma (fat).

Neoplasm

Definition: An abnormal mass of tissue that forms when cells grow and divide more than they should or do not die when they should.

What it means: A medical term for "tumor." Can be benign (non-cancerous) or malignant (cancerous).

Tumor

Definition: An abnormal lump or mass of tissue. Can be benign (not cancer) or malignant (cancer).

What it means: Tumors are often named by adding the suffix "-oma" to the cell type (e.g., lipoma from fat cells). However, some "-oma" tumors are actually malignant (e.g., melanoma).

Lesion

Definition: An area of abnormal tissue. A lesion can be benign (non-cancerous) or malignant (cancerous).

What it means: A general term that pathologists use to describe any abnormal finding. Could be a lump, sore, or change in tissue appearance.

Inconclusive / Nondiagnostic

Definition: The pathologist couldn't make a definitive diagnosis from the sample provided.

What it means: The biopsy didn't provide enough information for a clear answer. This doesn't mean something is wrong—it means more information is needed. A repeat biopsy or different procedure may be recommended.

Insufficient

Definition: The tissue sample was too small or inadequate to make a diagnosis.

What it means: The biopsy didn't collect enough tissue to examine properly. A repeat biopsy may be necessary.

Understanding the types of cells and tissues mentioned in your report.

Epithelial / Epithelium

Definition: The tissue that lines the surfaces and cavities of your body (skin, digestive tract, lungs, etc.).

What it means: Most cancers (carcinomas) arise from epithelial cells. This is the most common type of tissue found in biopsies.

Stromal / Stroma

Definition: The supportive tissue of an organ, including connective tissue, blood vessels, and lymphatic vessels.

What it means: The structural framework that supports the functional cells of an organ. Tumors can arise from stromal cells (sarcomas) or invade the stroma.

Glandular

Definition: Relating to glands or glandular cells that produce secretions (hormones, enzymes, mucus, etc.).

What it means: Many cancers are adenocarcinomas, which arise from glandular cells. Common in breast, lung, prostate, and colon cancers.

Squamous

Definition: Flat, scale-like cells that make up the outer layer of skin and line some organs.

What it means: Squamous cell carcinoma is a common type of skin cancer and can also occur in the lungs, head and neck, cervix, and other areas.

Basal

Definition: Small, round cells found in the lowest layer of the epidermis (outer skin layer).

What it means: Basal cell carcinoma is the most common type of skin cancer. It rarely spreads but can cause local damage if untreated.

Endothelial

Definition: Cells that line the interior surface of blood vessels and lymphatic vessels.

What it means: These cells can give rise to angiosarcoma, a rare type of cancer of blood or lymph vessels.

Mesenchymal

Definition: Cells that give rise to connective tissues, bone, cartilage, muscle, and blood vessels.

What it means: Sarcomas arise from mesenchymal cells. This is different from carcinomas, which arise from epithelial cells.

Fibrous

Definition: Relating to fibrous connective tissue, which provides structural support.

What it means: Fibrous tissue is common in many organs. Fibromas are benign tumors of fibrous tissue.

Adipose

Definition: Fatty tissue that stores energy and provides cushioning.

What it means: Lipomas are benign fatty tumors. Liposarcomas are malignant fatty tumors.

Muscular

Definition: Relating to muscle tissue.

What it means: Can refer to smooth muscle (in organs) or skeletal muscle. Leiomyomas are benign smooth muscle tumors (fibroids). Rhabdomyosarcoma is a malignant skeletal muscle tumor.

Neural

Definition: Relating to nerves or nervous tissue.

What it means: Neurofibromas are benign nerve tumors. Gliomas are malignant tumors of glial (supportive) nerve cells in the brain.

Lymphoid

Definition: Relating to lymph tissue, including lymphocytes (white blood cells).

What it means: Lymphomas are cancers of lymphoid tissue. Leukemia is a cancer of blood-forming cells.

Myeloid

Definition: Relating to bone marrow cells that give rise to red blood cells, platelets, and certain white blood cells.

What it means: Myeloid leukemia and myeloproliferative disorders arise from these cells.

Hematopoietic

Definition: Relating to the formation of blood cells.

What it means: Cancers of hematopoietic cells include leukemias and some lymphomas.