Category Archives: Organ Systems
Neoplastic Lung Classification – Resection Specimens
The following is a combination of the IASLC/ATS/ERS lung tumor classification for adenocarcinoma in resection specimens and the general WHO 2004 classification. See Neoplastic Lung Classification – Biopsy for categorization in small biopsy samples.
Continue reading Neoplastic Lung Classification – Resection Specimens
Neoplastic Lung Classification – Biopsies
Recommended IASLC/ATS/ERS terminology for tumor diagnoses on small lung biopsies . See Neoplastic Lung Classification – Resection Specimens for categorization of large excision specimens.
Dysplasia Characteristics
Identification of dysplasia in >10% of a particular hematologic lineage is an important defining criteria for myelodysplasia (MDS) in a bone marrow specimen. The following are the described agreed upon features of dysplasia per the WHO Classification. Continue reading Dysplasia Characteristics
Cytopenia Definition
WHO Criteria for Cytopenias
- Platelet count <100,000/μL
- Hemoglobin <10g/dL
- Absolute neutrophil count <1,800/μL
The WHO Classification does state patients with MDS may present having mild cytopenias with values above the defined levels. Continue reading Cytopenia Definition
SB3F1 Mutation
- SB3F1 is a RNA splicesome, mutated SB3F1 may result in an alternative function proteins instead of a loss of function mutation (Obeng, et al.)
- Point mutations associated with MDS are in the regions of exons 14 to 16
- ~25% of all cases of MDS have a SB3F1 mutation
- ~80% of MDS-RS SLD have SBF3F1 mutation
- 30-70% of MDS-RS MLD have SB3F1 mutation
- 20% of MDS/MPN cases have SB3F1 mutation
- Heterozygous mutation of SB3F1 mutation is associated with disease
- Obeng et al. demonstrated in mice that an isolated SB3F1 mutation is sufficient to cause MDS-type findings
- The presence of a SB3F1 mutation has a positive predictive value (PPV) of finding ring sideroblasts of 97.7%.
Ring Sideroblasts
Definition
- ≥5 iron staining granules (+)
- Encircling at least 1/3 of the nucleus
Diagnostic criteria for significant in MDS are ≥15% ring sideroblasts without evidence (or knowledge) of a SB3F1 mutation. This threshold drops to ≥5% with a SB3F1 mutation) Continue reading Ring Sideroblasts
p16
p16 is a marker primary used as a surrogate marker for high risk HPV infection. The physiologic role of p16 when it is expressed leads to cell cycle arrest. Normal levels are below the threshold for detection by immunohistochemical methods (IHC). Sometimes occasional non-proliferating epithelial cells may express p16 by IHC (these cells are usually in the upper aspects of the stratified epithelium.
Polycythemia Vera (PV)
Major Criteria
- One of the following
- Hgb. > 16.5 g/dL or Hct. > 49% in men
- Hgb. > 16.0 g/dL or Hct. >48% in women
- Elevated RBC mass (at least 25% above the mean predicted value)
- BM with trilineage hyerpcellularity (panmyelosis) including pleomorphic megakaryocytes (variability in size)
- JAK2 V617F or JAK2 exon 12 mutation
Minor Criteria
- Low serum EPO level
Chronic Neutrophilic Leukemia (CNL)
Diagnostic Criteria
- Activating CSF3R mutation (usually T618I or T615A)
- WBC ≥ 25,000 (at least 80% neutrophils + bands, <10% neutrophil precursors)
- No dysgranulopoiesis or monocytosis (<1,000/μL)
- Bone marrow hypercellularity
- <5% blasts
- Increased granulopoiesis
- No evidence of dysgranulopoiesis
- No molecular abnormalities or diagnostic characteristics of another MPN or MPN/MDS
If a CSF3R mutation is NOT identified, the diagnosis of CNL can still be made if other reactive causes are excluded or other evidence of clonality is identified (persistent for at least 3 months). Continue reading Chronic Neutrophilic Leukemia (CNL)