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
List your differentials for a 1yr crossbreed dog with well circumscribed 1cm nodular, erythematous mass on pinna which grew quickly and has been present for 3 weeks
- Histiocytoma
- Plasmacytoma
- Trichoblastoma
- Cutaneous lymphoma
- Mast cell tumour
- Foreign body
- Tick
What is your diagnosis based on the cytology of a 1cm well circumscribed erythemtous lump on the pinna of a 1yr old crossbreed dog, which showed round discrete cells that look like histiocytes, as a clonal population with pleomorphism and mitotic cells present
Histiocytoma
Outline the treatment for a single histiocytoma in a young dog
- Leave it as will often go away on their own
- if others occur or does not go away, then do not ignore
- See back in a month
- Will often ulcerate before improve
- Do not apply steroids as need body’s inflammatory response in order to get rid of histiocytes
List the bacterial causes of non-neoplastic cutaneous masses
- Abscess (post-traumatic/foreign body)
- Bacterial cellulitis
- Furunculosis secondary to Staph folliculitis +/or demodex
- Actinomyces/Nocardia/Actinobacillus infection
- Cutaneous mycobacterial lesions
- Feline mycobacteria granuloma
- Cutaneousbacterial grauloma
Which of the bacterial causes of cutaneous masses are zoonotic?
- Actinomyces, Nocardia, Actinobacillus
- Cutaneous mycobacterial lesions
- Feline mycobacterial granuloma
List the fungal causes of cutaneous masses
- S/c dermatophytic granuloma (“kerion”)
- Sporotrichosis
- Opportunistic s/c fungal infections
- Cutaneous involvement of systemic mycosis
What is the main protozoal cause cutaneous masses?
Leishmaniasis
List infectious causes of cutaneous masses other than bacterial, fungal and protozoal
- Rhabditic dermatitis
- Protothecosis
- Pythiosis
What is the effect of mast cell degranulation in the dog?
Angioedema, urticaria
Identify the immunological causes of urticaria and angioedema in the dog
- Type I or III hypersensitivities
- Mast cell tumours rare
Identify the non-immunological causes of urticaria and angioedema in the dog
- Physical forces (pressure, sunlight, heat, exercise)
- Genetic abnormalities
- Drugs/chemicals icl. food
- Venemous insects
- Plants
Describe the appearance of urticaria in the dog
- Localised or generalised wheals
- +/- pruritus
- Hair tufts over areas of swelling
Describe the appearance of angioedema in the dog
- Localised or generalised large oedematous swelling, usually involving the head
- +/- pruritus, exudation
What are the potential consequences of angioedema?
- Potentially fatal if involves airways
- Rarely assocaited with anaphylactic shock
Compare the occurrence of angioedema and urticaria in horses, dogs and cats
- Common in horses
- Less common in dogs
- Rare in cats (in cats, usually due to sting leading to regional oedema)
What is calcinosis cutis?
Inappropriate deposition of calcium/phosphate in skin/subcutis
Describe the appearance of calcinosis cutis
Gritty white deposits, often with surrounding inflammation
Describe the different types of calcinosis cutis
- Dystrophic calcification: deposition in injured, degenerating or dead tissue e.g. HAC
- Metastatic calcification: deposition associated with altered serum levels of calcium/phosphorous e.g. chronic renal disease
- Idiopathic e.g. calcinosis circumscripta
Define a seroma
Accumulation of sterile fluid (filtrate of blood) under a wound
Describe the cutaneous appearance of panniculitis
Presents as single or multiple nodules, easily confused with bacterial abscess
What are the treatment options for panniculitis?
- If sterile and solitary, may choose surgical excision
- Or treat by immunosuppression
Outline how the cause of panniculitis is identified
Biopsy for histopathology and fungal/bacterial tissue culture, as need to identify if sterile or infectious
List the potential inflammatory causes of cutaneous masses
- Traumatic lesions leading to cellulitis, granulation tissue
- Abscesses
- Umbilical infections
- Lymphangitis
- Lymphadenitis
- Haematoma
What is the causative agent of “Blackleg”?
Clostridium chauvoei
What is the cause of ulcerative granuloma in pigs?
Borrelia suilla
Discuss the treatment of urticaria
- Rapid acting glucocorticoids
- May also resolve spontaneously
- Epinephrine if life threatening
- Anti-histamines questionable
- Need to get rid of the allergen rather than treat the lesion
Why is the use of anti-histamines in the treatment of urticaria questionable?
Can induce urticaria if given IV
Discuss the treatment of angioedema
- Airway management with acute angiodema and anaphylaxis involving laryngeal oedema or bronchial constriction
- Adrenaline and rapid acting soluble glucocorticoids
Discuss the management of arthropod-bite granulomas
- Check no evidence of retained arthropod mouthparts
- May resolve without treatment
- short course of topical corticosteroids can be used
- If not resolving consider surgical removal and submission for histopath and tissue culture to confirm diagnosis
- Must be off corticosteroids for 2 weeks minimum before sampling for histology
List the differentials for a firm swelling of the right cheek of a 5yo MF DSH cat, present for 5 days, where palpation of the mass is resented. Clinically well other than pyrexia
- Cat bite abscess
- Tooth root abscess
- Foreign body
- Mast cell tumour
- Haematoma (post-RTA)
- Feline mycobacterial granuloma
What investigations would you require in the case of a firm swelling of the right cheek of a 5yo MF DSH cat, present for 5 days, where palpation of the mass is resented. Clinically well other than pyrexia
- FNA
- Impression smear
- Examine for evidence of dental disease
- Biopsy based on cytology results
List your differentials for a unilateral fluctuant, painless pinnal swelling that has developed overnight in an 8yo Labrador. the pinna does not pit on pressure
- Haematoma
- Infection (foreign body)
- Hypersensitivity reaction to bite
- Seroma
What are the potential causes of auricular haematomas?
- Scratching or head shaking
- May be due to food induced atopy
- Environmental atopy
- Otic disease
Discuss the management of auricular haematomas
- FNA to confirm
- Surgery to allow drainage using butterfly connection or IV catheter
- Several mattress sutures can be used to eliminate the space and prevent recurrence
- Instillation of glucocorticoids without causing skin distention
- Short course of anti-inflamm low dose glucocorticoids
List your differentials for a 10yo ME staggie with a fluctuant swelling on pectoral region, present for 3 days at site of recent removal of subcut mass, minimal discomfort on palpation, temp 38.6
- Seroma
- Haematoma
- Foreign body/localised infection/abscess
What investigations would you carry out in the case of a 10yo ME staggie with a fluctuant swelling on pectoral region, present for 3 days at site of recent removal of subcut mass, minimal discomfort on palpation, temp 38.6. Explain how this would allow you to differentiate between your top 3 differentials
- FNA for gross cytological analysis
- Seroma: straw-coloured, blood tinged fluid
- Haematoma: cytology same as blood smear, may have soe mmacrophages +/- fibroblasts appearance with time
- Infection: purulent aspirate if abscess, high numbers of neutrophils, bacteria visible in abscess or cellulitis
Discuss the management of a post-surgical seroma
- Conservative, unless refractory or causing wound disruption
- can take weeks to heal
- Pressure bandage for 1 week if site allows
- Keep animal quiet and confined
- Repeated drainage if causing discomfort, but tend to reform and risk of infection
- If severe: surgical debridement, flush with isotonic solution, close with careful apposition and insert penrose drains
List your differentials for a 4yo MN English bull terrier with a 1cm diamter, firm, ill-defined erythematous nodule with central black mark, present on ventrolateral abdomen for 1 week, unchanged
- Inflammatory
- Foreign body
- Bite hypersensitivity/infection
- Mast cell tumour
- Deep pyoderma
What further investigations would you require in the case of a 4yo MN English bull terrier with a 1cm diamter, firm, ill-defined erythematous nodule with central black mark, present on ventrolateral abdomen for 1 week, unchanged
- FNA
- Biopsy
What is a central black area on a small cutaneous mass often highly suggestive of?
Arthropod bite granuloma, confirm with biopsy
List your differentials for a large fluctuant swelling, occupying the majority of the lateral aspect of the left thigh of a 1yo heifer
- Haematoma
- Oedema following fracture
- Cellulitis/abscess
What further investigations would you carry out in the case of a large fluctuant swelling, occupying the majority of the lateral aspect of the left thigh of a 1yo heifer
FNA
List your differentials for an 8 week old heifer calf with a soft painless swelling on the ventral midline, time of unset unknown, systemically well
- Umbilical hernia
- Umbilical abscess
Outline you investigation of an 8 week old heifer calf with a soft painless swelling on the ventral midline, time of unset unknown, systemically well
- Palpation: soft and reducible suggests hernia (may be able to feel ring),firm if abscess
- Take temperature (investigate systemic infection)
- FNA
- Utrasound
Outline the management of umbilical hernias in a calf
- Small: inconsequential, no action
- Large: close if economically viable to avoid risk of strangulation of protruding abdominal contents or rupture with increased abdominal weight
- Do not breed as potentially heritable
