The Pathology Dictionary provides simple, patient-friendly definitions of the most common words and phrases used in pathology reports. These articles explain general medical terms and concepts. If you are looking for detailed information about a specific diagnosis in your report, visit our Diagnosis Guides.
What is the difference between a definition and a diagnosis guide?
A definition explains what a word means. These definitions are designed to help patients understand unfamiliar medical language in their pathology report. A diagnosis guide explains what a specific diagnosis means in the context of your pathology report.
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A
Abscess
Acanthosis
Acantholysis
Acute inflammation
Addendum
Adenoma
Adenocarcinoma
Adenocarcinoma in situ (AIS)
Adenosquamous carcinoma
Adipose tissue
AE1/AE3
ALK (anaplastic lymphoma kinase)
AMACR
Amendment
Amorphous
Amyloid
Anaplasia
Anaplastic
Androgen receptor (AR)
Anemia
Angioinvasion
Antral type mucosa
Antibody
Apocrine
Apocrine metaplasia
Apoptosis
Arias-Stella reaction
Arteriovenous malformation (AVM)
Atrophic
Atrophy
ATRX
Atypia
Atypical
Atypical mitotic figure
Atypical mitosis
B
B cells
Ballooning hepatocyte
Banff score
BAP1
Basal cells
Basal lymphoplasmacytosis
Basaloid neoplasm
Basophils
BCL2
BCL6
Benign
Benign neoplasm
Benign vascular proliferation
Biopsy
Blasts
Blastoid
Body type mucosa
Bone marrow aspiration
Bone marrow biopsy
Borderline tumor
BRAF
BRCA1 and BRCA2
Breslow thickness
C
Calcification
Calcitonin
Carcinoma
Carcinoma in situ
Carcinoid
Caldesmon
Candida species
Cardiac type mucosa
Cautery artifact
CD10
CD117 (c-kit)
CD138
CD19
CD20
CD3
CD30
CD34
CD45
CD5
CD68
CDX-2
Cholesterol cleft
Cholestasis
Chondroid
Chondroid tumour
Chronic inflammation
Chromatin
Chromogranin
Clark’s level
Colitis
Colonic mucosa
Columnar mucosa
Comedonecrosis
Complete blood count (CBC)
Contaminant
Cribriform
Crohn’s disease
Crypt abscess
Crypt distortion
Cryptitis
ctDNA
Cyclin D1
Cytokeratin
Cytokeratin 34betaE12
Cytokeratin 5 (CK5)
Cytokeratin 7 (CK7)
Cytokeratin 20 (CK20)
Cytologic atypia
Cytomegalovirus (CMV)
Cyst
Cystic degeneration
Cytoplasm
D
D2-40
Dedifferentiation
Dedifferentiated
Degenerative changes
Desmin
Desmoplasia
Desmoplastic
DIF
Differentiated
Diffuse
Direct immunofluorescence
Distal
DOG1
DPYD
Duct
Dyskeratotic cells
Dysplasia
E
E-cadherin
ECL (enterochromaffin-like) cell hyperplasia
Edema
Edematous
EGFR (epidermal growth factor receptor)
Endometrial glands
Endophytic
Endosalpingiosis
Enteritis
Eosinophil
Eosinophilic abscess
Epidermotropism
Epithelial cells
Epithelioid cells
Epithelium
Epstein-Barr virus (EBV)
Epstein-Barr virus-encoded small RNAs (EBER)
ERG
Estrogen receptor (ER)
Erosion
Excision
Excisional biopsy
Exogenous hormone effect
Exophytic
Extranodal extension (ENE)
Extraparenchymal extension
F
Fat necrosis
Fibroblasts
Fibromyxoid tumour
Fibrosis
Fibrinoid necrosis
Fibrinopurulent exudate
Fibroepithelial polyp
Fibrovascular core
Fine needle aspiration biopsy (FNAB)
FLI1
Floater
Flow cytometry
Fluorescence in situ hybridization (FISH)
FNCLCC (Fédération Nationale des Centres de Lutte Contre le Cancer)
Foamy histiocyte
Focal
Focus score
FOLR1
Foveolar metaplasia
Frozen section
Fuhrman grade
Fusion
G
GATA-3
Gastric heterotopia
Gastroesophageal junction (GEJ)
Gene
Germinal centers
GFAP
Ghost cells
Gland
Glandular cells
Gleason grade
Gleason score
Glomerulosclerosis
Goblet cells
Grade
Granulation tissue
Granuloma
Grocott (GMS)
Gross
Gross description
H
Hallmark cells
Hamartoma
Hans algorithm
HBME-1
Helicobacter pylori (H. pylori)
Hematoxylin and eosin (H&E)
Hematopoiesis
Hematopoietic cells
Hepatocytes
Heterogeneous
Heterotopic ossification
Her2
Herpes simplex virus (HSV)
High grade
High grade dysplasia
High grade squamous intraepithelial lesion (HSIL)
High risk HPV
Histiocytes
HMB-45
Homogeneous
HPV associated squamous cell carcinoma
HPV test
Human herpesvirus-8 (HHV-8)
Human papillomavirus (HPV)
Hurthle cell
Hyams grade
Hypercellular
Hyperchromatic
Hyperchromasia
Hypergranulosis
Hyperkeratosis
Hyperplasia
Hypertrophy
Hypocellular
Hypocellular marrow
I
IDH1 and IDH2
IgG4-related disease
Immunohistochemistry (IHC)
Immunoglobulin
Immunophenotyping
Immunoreactivity
Immunostain
Implantation site
Inadequate
Infiltrative
Infiltration
Inflammation
Inflammatory cell
INSM1
Interface changes
Intraepithelial
Intraepithelial lymphocytosis
Intraepithelial neoplasia
Intramucosal carcinoma
Intranuclear inclusions
Ischemic necrosis
Isolated tumour cells (ITCs)
In situ hybridization (ISH)
Insufficient for diagnosis
Intercellular bridges
Intestinal metaplasia
Intracytoplasmic
In-transit metastasis
In toto
Invasion
Invasive
J
JAK2
K
Karyotype
Keratinization
Keratinizing
Keratinizing dysplasia
Keratinocytes
Keratosis
Ki-67
Ki-67 labeling index
Koilocytes
KRAS
L
Lamina propria
Larynx
LEEP (loop electrosurgical excision procedure)
Lesion
Leukemia
Leukocyte
Limited for interpretation
Lipoblasts
Liposarcoma
Liquid biopsy
Low grade
Low grade dysplasia
Low grade squamous intraepithelial lesion (LSIL)
Lymphatic invasion
Lymphoblasts
Lymphoid aggregate
Lymphocyte
Lymphocytosis
Lymphoid cells
Lymphohistiocytic
Lymphoplasmacytic
Lymphoproliferative disease
Lymphovascular invasion (LVI)
Lymphoma
Lymph node
M
Macrophages
Malignant
Malignant neoplasm
Malignant spindle cell neoplasm
Malignant transformation
Mallory-Denk bodies
Mature adipose tissue
Margin
Mass
Mast cells
Matted lymph nodes
Melanocyte
Melanoma
Melan-A
Melanosis coli
Metaplasia
Metastasis
Metastatic carcinoma
Metastatic adenocarcinoma
Mesangial sclerosis
Mesothelial cells
Mesothelial hyperplasia
Mesothelial proliferation
MGMT
MIB-1
Microcalcification
Micropapillary
Minimally invasive
Minimal residual disease (MRD)
Mismatch repair (MMR)
MITF
Mitosis
Mitotic figure
Mitotic rate
MLH1
MLH1 promoter methylation
Molecular testing
Mucosa
Mucin
Mucinous
Mucicarmine
Multifocal
Multinucleated giant cells
Mutation
MYC
Myeloproliferative neoplasm
Myofibroblastic lesion/proliferation
Myoepithelial cells
Myxoid
N
Natural killer cells (NK cells)
Neoplasm
Neck dissection
Necrosis
Necrotizing granulomatous inflammation
Negative for malignancy
Neuroblasts
Neutrophil
Neuroendocrine cell
Neuroendocrine carcinoma (NEC)
Neuroendocrine differentiation
Neuroendocrine neoplasm (NEN)
Neuroendocrine tumour (NET)
NKX3.1
Nodal stage (N stage)
Non-diagnostic
Non-Hodgkin lymphoma
Non-invasive
Nonkeratinizing
Nonkeratinizing squamous cell carcinoma (NKSCC)
Non-necrotizing granulomatous inflammation
Non-reactive
Non-small cell carcinoma
Nonviable
Nottingham histologic grade
NRAS
NTRK
Nuclear atypia
Nucleus
Nucleoli
O
OCT3/4
Oncocytic
Oral cavity
Oropharynx
Osteoblasts
Osteoid
Oxyntic mucosa
P
p16
p40
p53
p63
Pancreatic heterotopia
Pancreatic metaplasia
Pancytokeratin
Paneth cell metaplasia
Pap test
Papillae
Papillary
Papilloma
Papillomatous
Parakeratosis
Parenchyma
PASS score
Pathology report
PAX5
PAX8
Periodic Acid Schiff (PAS)
Periodic Acid Schiff plus Diastase (PAS-D)
Peripheral nerve sheath tumour
Parakeratosis
PD-L1
Perineural invasion (PNI)
PIK3CA
Plasma cells
Plasmacytoid cells
Platelets
Pleomorphic
Pneumocytes
POLD1
POLE
Polymerase chain reaction (PCR)
Polyp
Polypectomy
Polypoid
PRAME
Precursor
Progesterone receptor (PR)
Proximal
Prognosis
PTEN
Poorly differentiated
Poorly differentiated adenocarcinoma
Poorly differentiated carcinoma
Poorly differentiated neuroendocrine carcinoma
Positive for malignancy
Psammoma bodies
pTNM
Q
R
Racemase
Rearrangement
Red blood cells (RBCs)
Reactive changes
Reed-Sternberg cells
Resection
Residual cancer burden index
Respiratory type mucosa
RET
Rhabdoid
Richter transformation
Ring sideroblasts
S
S100
SALL4
Sarcoma
Sarcomatoid
Sarcomatoid carcinoma
SATB2
Satellite metastasis
Schistocytes
SDHB
Sebaceous glands
Sentinel lymph node
Signet ring cell
Sinonasal tract
Small bowel mucosa
Small cell neuroendocrine carcinoma
Smooth muscle actin (SMA)
Smooth muscle neoplasm
Solar elastosis
Somatic mutation
SOX10
STAT6
Stoma
Stroma
Stromal breakdown
Squamous cells
Squamous dysplasia
Squamous epithelium
Squamous metaplasia
Squamous mucosa
Special stain
Specimen
Spindle cells
Spindle cell lesion
Spindle cell neoplasm
Spindle cell proliferation
Spongiosis
Spongiotic
Spread through air spaces (STAS)
Squamous intraepithelial lesion (SIL)
Suspicious for malignancy
Synaptophysin
Syndrome
T
T cells
Tangentially sectioned
Tingible body macrophages
Transformation zone
Translocation
Trephine biopsy
Triple-negative breast cancer
TTF-1
Tubal metaplasia
Tumor
Tumor bed
Tumor capsule
Tumor deposit
Tumor infiltrating lymphocytes (TILs)
Tumor necrosis
Tumor of uncertain malignant potential
Tumor regression
Tumor stage (T stage)
Tumor suppressor gene
Tunnel clusters
Thyroglobulin
U
Ulcer
Undifferentiated
Urothelial cell
V
Vacuolar degeneration
Variant allele frequency
Vascular lesion
Vasculitis
Vascular invasion
Villous atrophy
Villous blunting
Viral cytopathic effects
Virus
W
Well differentiated
White blood cells (WBCs)
WT-1
0-9
1p/19q codeletion
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