Cutaneous masses 2 Flashcards
Cytology of cutaneous masses
Describe the cytoplasmic criteria of malignancy
- Basophilia: darker blue cytoplasm
- Vacuolation
- Distended with secretory product (signet ring appearance)
- NB cytoplasmic features can be influenced by non-neoplastic processes such as inflammation
Describe the cytological appearance of epithelial skin tumours
- Sheets or cohesive clusters of cells
- Defined cell borders (white lines between)
- Cells can be angular squamous cells, cuboidal or columnal, roundish/polygonal
Give examples of epithelial skin tumours
- Trichoblastoma (basal cell tumour)
- Trichoepithelioma (hair follicle tumour)
- SCC
- Sebaceous cell tumours (adenoma, carcinoma, epithelioma)
- Anal sac apocrine adenocarcinoma
- Perianal gland adenoma
What is the the origin of mesenchymal skin tumours?
Arise from connective tissue, muscle, bone and cartilage, nerve and endothelial cells
Describe the cytological appearance of mesenchymal skin tumours
- Cells non-cohesive aggregates or individualised
- Cell borders variably defined, often indistinct
- Embedded in matrix
- Spindle shaped cells with cytoplasmic tails common
- Cells can be oval or plump, due to bulging nucleus (more likely to be neoplastic)
Give examples of mesenchymal skin tumours
- Fibroma and fibrosarcoma
- Lipoma/liposarcoma
- Perivascular wall tumours, haemagiopericytoma, myopericytoma
- Anaplastic sarcoma with giant cells (malignant fibrous histiocytoma)
- Haemangioma/haemangiosarcoma
- Peripheral nerve sheath tumour, perineurioma
- Myxoma/myxosarcoma
- Melanoma
What is required in order to identify the types of mesenchymal tumours?
Difficult on cytology, likely to need histopathology
What is the distinguishing feature of haemangiosarcomas?
Lots of vasculature, may appear very aggressive
Describe the cytological appearance of lipomas
- Adipocytes with small looking nuclei (look small due to larger cytoplasm)
- Abundant vacuolated cytoplasm
- Free fatty droplets
- cells fall off slides during staining and fixation so often few slides
- Subcut fat looks identical
Describe the cytological appearance of malignant tumours of fat
- bigger and more variation in nuclear size
- Lots of blobs of fat rather than a few bigger ones
- Pleomorphic spindle cells may be present
- Presence of other cells similar to lipocytes with larger vaacuoles
Describe the typical cytological appearance of round cell tumours
- Individual cells, round or round-ish
- High cell yield on FNA
Give examples of round cell tumours of the skin
- Mast cell tumour
- Lymphoma
- Plasmacytoma
- Histiocytic tumours
- Transmissible venereal tumour (usually genital location)
Describe the cytological appearance of cutaneous mast cell tumours
- Nucleus barely visible
- Lots of variation in nucleus if visible
- Granules may be dissolved by DiffQuik so use Wrights Giemsa staining to differentiate from histiocytes
Outline how to differentiate histiocytes from other round cells
- Not lymphocytes as the cytoplasm is not slim enough
- Not mast cells as there are no granules present
- Not plasma cells as the chromatin is not condensed enough
Describe the cytological appearance of a cutaneous histiocytoma
- Typically benign in the dog
- Initially pure population of histiocytes, later will be a mix of histiocytes and lymphocytes
- When regressing, lymphocytes may predominate
- +/- neutrophilic inflammation if ulcerated
Describe the cytological appearance of cutaneous lymphoma
- Epitheliotropic lymphoma
- Infiltrate with T cells in epidermis
- Nuclear material bigger indicating malignancy
Following diagnosis of a mast cell tumour on cytology, of approximately grade 2, what would be a logical approach?
- Potential for metastasis so screen local lymph node +/- liver and spleen
- Submit for grading using incisional biopsy
- Wide excision required
- Radiotherapy as first choice treatment, are not responsive to chemotherapy
List the differentials for a 1.5cm diameter firm, painless interscapular nodule on a 3yo dog that has recently been castrated
- Injection/microschip reaction (sterile inflammatory lesion)
- Spindle cell tumour
- Cyst
- Adnexal tumour
- MCT
List the differentials for a 2cm erythematous nodule on the dorsal aspect of the radius of a 6yo MN springer spaniel, with little changes since first seen 2 weeks ago but with some irritation
- Penetrating wound causing infection/inflammation/cellulitis
- Insect bite reaction/innfection
- Mast cell tumour
- Histiocytoma
- Plasmacytoma
- Cutaneous lymphoma
- Adnexal or mesenchymal tumour with inflammation
What would you diagnosis be of a lump that appeared shortly after neutering in the interscapular region where cytology identified a fatty vacuoles, macrophages and neutrophils over a proteinaceous background?
Mixed inflammation within adipose tissue i.e. panniculitis, most likely to be an injection reaction
What treatment would be required for a lump caused by panniculitis injection reaction?
No further treatment required
List the differentials for a 3cm diameter, well-defined soft mass on the medial thigh of a 9yo MN Staffie, which has enlarged slightly over the past 6 months
- Lipoma
- Cyst
- Mast cell tumour
- Low grade spindle cell tumour
- Low grade adnexal tumour
- Foreign body abscess (unlikely as little change in 6 months)
What would you diagnosis be of a lump that has changed little over 6 months, and where cytology showed large adipocytes with abundant clear cytoplasm and very small nuclei
A lipoma, although care as may be other things going on and may have missed true lesion with FNA
List the differentials for a 12yo MN DSH cat with an ill-defined swelling on the left dorsal scapular region, first noted 3 days ago
- Abscess/cellulitis
- Injection reaction
- Sarcoma
- Enlarged pre-scap lymph node
- mast cell tumour
- Foreign body
- Cyst
- Haematoma
- deep pyoderma
- Hypersensitivity to insect bit
What diagnosis would you suggest based on the cytology of an ill-defined swelling on the dorsal scapular region of a cat, that showed normal and degenerate neutrophils, intracellular bacteria and a proteinaceous background
- Active infection
- NB may see pus when take the sample
- Most likely to be an abscess
List your differentials for an 8yo ME boxer with a 4cm diameter, well-defined soft mass on medial thigh, presently unchanged for several months
- Lipoma
- Cyst
- MCT
- Soft tissue sarcoma
- Low grade adnexal tumour
- Lymphoma
What is you diagnosis of a lump on an 8yo ME boxer with a 4cm well defined soft mass that has changed little over several months, where cytology showed individual cells with granulated cytoplasm, large nuclei, high N:C ratio, variable granularity and free granules in the background, with significant pleomorphism
Mast cell tumour
List the differentials for an 11yo ME Labrador with an irregular, ill-defined firm nodule, 6cm diameter over right caudal radius, that has increased in size over past month
- Soft tissue sarcoma of muscle or tendon (fibrosarcoma)
- SCC
- Foreign body (exogenous or bony sequestrum, sterile or septic)
- Pressure hyperplasia
- Mast cell tumour
- Epidermal inclusion cyst (but are often well circumscribed)
- Osteosarcoma (ubut are usually very painful and often not cutaneously visible)
What is your diagnosis for an irregular, ill-defined firm nodule 6cm diameter over right caudal radius that has increased in size over past month, where cytology showed aggreagate of spindle shaped cells with mild anisocytosis and anisokaryosis, bulging nuclei and some cells with bulging nuclei
Spindle cell tumour
Outline your next steps following the diagnosis of a spindle cell tumour on cytology
- Incisional biopsy for histopathological diagnosis
- Excisional margins difficult due to infiltrative nature, radiotherapy or amputation most likely
- If on immunosuppressants need to watchclosely for lumps and identify immediately as these prevent the ability to control the tumour