Differential Diagnosis for Cutaneous Masses Flashcards
Benefits of FNA/FNCS
Quick
Simple
Cheap
Possible to do in-house
Helpful in establishing diagnosis
Possible outcomes of cytological findings
Arrive at definitive diagnosis
Investigate further
Leave mass alone
What can cytology tell us about a mass?
Inflammatory
○ Septic
○ Sterile
Non-inflammatory
○ Cystic
○ Hyperplastic/dysplastic
○ Neoplastic
* Round
* Epithelial
*Mesenchymal
Process of assessing cytology
- Is there a significant amount of immune cells?
- What tissue cell type is present?
- Is there neoplasia present?
- Is there a significant amount of immune cells?
Neutrophilic (suppurative or acute) inflammation
Includes “abscess”
Pyogranulomatous inflammation
Granulomatous (macrophagic or chronic) inflammation
Eosinophilic inflammation
“Septic” vs “no organisms seen”
- What tissue cell type is present?
Epithelial?
Round?
Mesenchymal?
Epithelial skin tumours
Adherent together
White line between cells
Some order to structure
Epithelial skin tumour examples
Trichoblastoma
Basal cell tumour
Trichoepithelioma
Hair follicle tumour
Squamous cell carcinoma
Seen in white cats (UV light)
Sebaceous cell tumours
Adenoma
Carcinoma
Epithelioma
Anal sac apocrine adenocarcinoma
Perianal gland (hepatoid) adenoma
Mesenchymal skin tumours
- Arise from:
○ Connective tissue
○ Muscle
○ Bone & cartilage
○ Nerve cells
○ Endothelial cells - Cells in non-cohesive aggregates or individually
- Cell borders are variably defined and often indistinct
- Embedded in matrix
- Spindle shaped cells with cytoplasmic tails common
- Cells can be oval or plump
- Often won’t make definitive characterisation of mesenchymal proliferation by cytology
Mesenchymal skin tumour examples
Fibroma and fibrosarcoma
Lipoma and liposarcoma
Perivascular wall tumours
Haemangiopericytoma
Myopericytoma
Anaplastic sarcoma with giant cells
(malignant fibrous histiocytoma)
Haemangioma/haemangiosarcoma
Peripheral nerve sheath tumour
Myxoma/myxosarcoma
Melanoma
Granulation/healing
Lipoma
- Adipocytes with small nucleus and abundant cytoplasm
○ Same size nucleus just less magnification needed to view cell - Free fatty droplets
- Cells may fall off slides during staining/fixation
○ Avoid methanol fixation
○ Consider drop rather than drip - Subcutaneous fat appears identical to lipomas
Round cell tumours
Individual cells
Round/roundish
High cell harvest
Look at nucleus:
○ Cytoplasmic ratio
Look at position of nucleus to determine cell type
Look in cytoplasm
Round cell tumour examples
Mast cell tumour
Lymphoma
Plasmacytoma
Histiocytic tumours
Transmissible venereal tumours (TVT)
Plasmacytoma
Discrete cells
More eccentric nuclei - pushed up against walls
Chromatin clumping
Perinuclear clear zones - pale areas near nucleus
- Is there neoplasia present
Are there cells present that shouldn’t be in this tissue?
Is it benign or malignant?