W2L4 - Serous Effusions Flashcards
Sensitivity and Specificity of Serous Effusions
Sensitivity of 58%
Specificity of 97%
Serous Effusion - Sampling Methods
Serous effusions can be removed at the time of surgery or when a serous cavity causes discomfort to the patient
- due to excessive build up of fluid
Done by needle into cavity under anaesthetic
Peritoneal fluid - abdominal paracentesis
Pleural fluid - thoracentesis
Pericardial fluid - pericardiocentesis
Collection of Serous Effusions
Fluid is collected into a clean, sterile, dry container which is sent to a laboratory ASAP
Formalin or alcohol must NOT be added as this prevents the cells from adhering to the slide but also interferes with the quality of staining by the Papanicolaou method
What is an Effusion
Accumulation of serous fluid above the normal amount is considered an effusion
Transudates
Transudates are characterised by: - low protein content < 30g/L - low specific gravity < 1.015 - low cellular yield - low fibrin content The smears usually consists of mesothelial cells, macrophages and occasional lymphocyte or neutrophils
Exudates
Exudates occur due to damage of the capillary walls within the serosal connective tissue
- high protein content >30g/L
- high specific gravity > 1.015
- high cellularity (increased inflammatory cells caused by inflammation, or malignancy).
Normal Cells
All pleural, peritoneal (ascitic) and pericardial fluids contain cells:
- mesothelial cells
- macrophages
- red blood cells
- neutrophil
- eosinophils
- lymphocytes
- megakaryocytes
Other cells may included;
- ciliated cells from respiratory tract (if lung is punctured)
- hepatocytes (seen in right sided effusions)
Mesothelial Cells - Hypertrophy and Hyperplasia
Mesothelial cells undergo a wide range of hypertrophy and hyperplasia due to a wide range of stimuli
- inflammation
- necrosis of underlying parenchyma
- presence of foreign substance within the cavity (blood, air)
The presence of effusion will result in proliferation of mesothelial cells
Mesothelial Cells - Cytology
Mesothelial cells exfoliating into a serous fluid are:
- round
- round nuclei
- cytoplasm dense and stains grey/green with Pap
- cytoplasm less dense at periphery
- well defined cell membrane
- chromatin uniformly granular
- nucleoli
- may be multinucleated
- vacuolation
- form ‘windows’ when touching other mesothelial cells
Vacuoles Seen in Mesothelial Cells
Can have:
- one or two unobtrusive vacuoles scattered throughout the cytoplasm but more likely near the nucleus
- a large solitary vacuole that displaces the nucleus to the periphery of the cell
- an elongated perinuclear vacuole which appears to curve around the nuclear membrane
Mesothelial Cell Cytology - Sheets and Groups
Small mesothelial cell clusters are common
Often in peritoneal (ascitic) effusions, larger sheets of flat mesothelial cells are present > 10 cells/sheet.
Mesothelial cells can appear to wrap around each other
Reactive Mesothelial Proliferation
Reactive mesothelial cells are commonly seen in association with recent surgery
Increased clusters of mesothelial cells
Variable anisokaryosis including multinucleation and binucleation
Slightly enlarged nuclei with prominent/sometimes multiple nucleoli
Smooth nuclear membranes, smaller clusters have ‘windows’
Mesothelial Cell Difficulties
Degenerate - vacuoles may be present and may mimic adenocarcinoma
Multinucleation
Mitoses
When they contain ingested material e.g. pigment
Atypical - especially in long standing effusions, pericardial effusions and inflammatory lesions
In practice, ALL effusions with a reactive mesothelial proliferation should have an EMA performed
Neutrophil - Empyema
Most effusion specimens will contain certain number of neutrophils
Number varies from the occasional neutrophil to a purulent effusion
Purulent effusions are macroscopically light yellow in colour with a turbid/creamy appearance
If an infection is suspected they may be malodorous
Inflammation, infarction or rupture of an organ are the principal causes of serous effusions containing numerous neutrophils
Empyema develops as a complication of pneumonia, however can develop as an extension of an adjacent abscess, subdiaphragmatic, paravertebral or lung
Macrophages
Macrophages are commonly identified in serous effusions
They are easily identified due to:
- eccentric round/oval/bean shaped nuclei
- fine, delicate, lacy cytoplasm
- cytoplasm may contain leukocytes, red blood cells, carbon particles, lipid droplets, nuclear particles, melanin or haemosiderin
Lymphoid Cells
Most are small mature lymphocytes in type
T and B cells cannot be differentiated on cytology alone but can be identified by immunocytochemical staining using monoclonal antibodies
Most lymphoid cells in a benign effusions are of T cell origin
Appear round with deeply stained nuclei
Size vary according to the amount of air drying that may occur
Minimal rim of basophilic cytoplasm on Papanicolaou staining
Non-Specific Effusion
Nearly all inflammatory serous effusions are non specific, they do not reveal the aetiologic background
Examples:
1. Acute purulent inflammation - contains numerous numbers of neutrophils
- macroscopically appear thick yellow/creamy consistency
- most pleural empyema are 2º to 1º bacterial pneumonia
2. Chronic inflammation - which is a predominance of lymphoid cells
- most common underlying cause is neoplasms in the lung
- next most common cause is tuberculosis
- need to exclude chronic lymphocytic lymphomas/leukaemias
Specific Inflammatory Effusions - Rheumatoid Disease
Necrotising granulomatous inflammation found in the synovium and subsynovial tissue of rheumatoid arthritic joints
Features seen on cytology effusions are pathognomic:
- elongated spindle shaped macrophages
- cytoplasm is moderately dense, acidophilic or cyanophilic and finely granular ground glass appearance
- multinucleated giant macrophages - round to oval nuclei with > 20 nuclei
- necrotic granular background formed by necrosis and disintegration of the macrophages
- may contain cholesterol crystals
Specific Inflammatory Effusions - Systemic Lupus Erythematosus
The LE cell: a neutrophil or a macrophage that has engulfed the denatured nucleus of injured cells
The injury is caused by circulating antinuclear antibodies present in excessive amounts in the serum of patients with SLE
LE cells contain engulfed haematoxylin bodies in Papanicolaou smears
In LE cells the nucleus is pushed over to the side and may seem to be a continuous crescent shaped band
Pneumothorax
Frequently accompanied by an effusion, induced by the presence of air and its impurities into the pleural cavity and pulmonary parenchyma
Cytology picture is non specific but may contain increased numbers of eosinophils due to allergenic impurities
The presence of air may also stimulate mesothelial cells to enlarge leading to hypertrophy the mesothelial cells
Tuberculosis
TB is often accompanied by a predominance of lymphocytes within the effusion sample
Only isolated mesothelial cells are identified, this is due to increase amount of fibrin deposit on the pleural surface
May also seen multinucleated giant cells and epithelioid histiocytes that form granulomas
Endometriosis
An extrauterine growth of functioning endometrial tissue
Commonly encountered in pelvic washings/ascitic fluids
Not common in the pleura, however can occur
Fluid macroscopically appears chocolate brown in colour
Cytology contains small columnar shaped cells, hemosiderin laden macrophages, may see endometriotic fragments of tissue, with both stromal and epithelial component
