Lumps and bumps Flashcards
What do nodular lesions often represent?
- cutaneous neoplasia
- inflammatory process
- trauma (haematoma)
- depositional disease (rare, amyloidosis - horses)
T/F: nodules with an inflammatory basis are often granulomatous
TRUE (with a diffuse or nodular dermal inflammatory pattern of associated with panniculitis)
Define panniculitis
inflammation of subcutaneous adipose tissue
Why might granulomatous inflammation occur?
- sterile
- FB
- bacterial infection
- also mycobacteria, actinomyces, fungi, viruses and parasites)
How can infectious agents be detected in nodular lesions?
- histology and cytology (routine or special stains)
- macerated tissue culture (especially deep layers of skin and fat)
- therefore FNA and skin biopsy important
When shouldn’t you do FNA or skin biopsy with a skin nodule?
equine sarcoid - invasive procedures may activate a more invasive behaviour
Where might neoplasia in the skin arise from? 4
HISTOLOGICAL CLASSIFICATION
- epithelial cells
- mesenchymal cells
- round cells (e.g. histiocytes, mast cells, lymphocytes)
- metastases from different sites
What is cutaneous amyloidosis?
horses especially, overproduction of APPs (liver) –> deposited in skin
What is botryomycosis?
= bacterial granuloma
- Staph pseudomycetoma is causative agent
- NOT FUNGAL!
- nodules/ non-healing wound
- may be grains/ granules in exudate
- site of trauma in some cases
Name 2 neoplasias arising from epithelial cells
SCC and papilloma
Outline the basic facts of hair follicle neoplasias
usually benign, single and cured by lumpectomy
What is the likely cause of lumps that appear on the eyelids?
Meibomian gland neoplasia
What is the approach to cutaneous neoplasia?
most important goal is diagnosis tumour type and where applicable histological grade. behaviour prediction usually depends on pre-treatment histology. then the antaomical location and extend of the lesion (staging) should be established. evaluate other complications where appropriate (haematological and metabolic).
What does the prognosis of a cutaneous neoplasm depend on?
- type and grade of lesion
- stage
- whether complications exist (haematological and metabolic)
- treatments available
What are the most appropriate treatments for the different cutaneous neoplasms? (solid tumours, haemolymphatic tumours and some solid tumours, solid tumours where surgical excision is not appropriate).
- solid tumours = surgery
- haemolymphatic neoplasms and some solid tumours = chemotherapy
- solid tumours where surgical excision is not appropriate = radiation therapy
What is the most common cutaneous neoplasm in the dog?
hepatoid gland adenoma (27% cases)
What are the 2 most common cutaneous neoplasms in the cat?
- ) basal cell tumour (34%)
2. ) squamous cell carcinoma (23%)
List the possible types of cutaneous neoplasm in dogs
- ) hepatoid gland adenoma (27%)
- ) sebaceuous adenoma (12%)
- ) trichoepithelioma (12%)
- ) basal cell tumour (11%)
- ) Meibomian gland adenoma (9%)
- ) Also intracutaneous cornifying epithelioma (5%), squamous cell carcinoma (5%), apocrine gland adenoma (5%).
What does the diverse array of epithelial neoplasms reflect?
the neoplastic transformation of an epithelial cell into:
- basal keratinocytes and their terminally-differentiated produce the squame
- cells of the inner and outer root sheaths of the hair follicle
- adnexal glands and their ducts
- THEREFORE A PATHOLOGIST WILL TRY TO ESTABLISH WHETHER CELLS ARE ‘TRYING TO MAKE ANYTHING’ such as hair or sebaceous gland etc.
T/F: most epithelial tumours are benign and respond to surgical excision
True - these include most hair follicle tumours, glandular adenomas and basal cell tumours
Name 3 tumours of the epidermis
- papilloma
- inverted papilloma
- SCC
What are the 3 broad categories of tumours with adnexal differentiation?
- hair follicle tumours
- tumours of sebaceous glands and modified sebaceous glands
- tumours of sweat glands and modified sweat glands
Name 2 epithelial tumours without squamous OR adnexal differentiation
- basal cell tumour
- basal cell carcinoma
List 5 different mesenchymal tumours
- fibrous tumours
- vascular and perivascular tumours
- muscle cell tumours
- neural and perineurial tumours
- lipocytic tumours
What is another name for a basal cell tumour?
Trichoblastoma
Name 5 different hair follicle tumours
- infundibular keratinising adenoma
- tricholemmoma
- trichoblastma
- trichoepithelioma
- pilomatricoma
Name 3 different tumours of sebaceous glands and modified sebaceous glans
- sebaceous hyperplasia/ adenoma/ epithelioma / adenocarcinoma
- hepatoid gland adenoma/ adenocarcinoma
- meibomian gland adenoma / epithelioma/ adenocarcinoma
Name 4 tumours of sweat glands and modified sweat glands
- apocrine gland adenoma / ductal adenoma / adenocarcinoma
- eccrine (atrichial) adenoma / adenocarcinoma
- anal sac adenoma/ adenocarcinoma
T/F: MCT can arise anywhere on the body and the subcutis and dermis may be invovled
True
Where is there an increased tendency for MCTs to form in dogs?
back half of body including perineum, distal limbs and prepuce
What age of dogs tend to get MCTs?
young and old dogs
Breed predisposition - MCT
- Boxers, Pugs and Weimeraners
- Hindlimb tumours: Boxers, pugs, pit bulls, boston terrier and english setters
Outline the clinical appearance of canine MCTs
- varies markedly
- single or multiple
- small or large
- well-demarcated or infiltrative
- firm or soft
- ulcerated or epithelialised
- oedematous or inflammatory
- may or may not be pigmented
- fluctuating swelling and erythema should increase the index of suspicion of a MCT.
What are possible concurrent CS of a MCT?
bleeding disorders
- immune-mediated thrombocytopaenia
- GIT ulceration
(since a proportion of MCTs are physiologically active, releasing histamine, heparin and other vasoactive amines)
How can MCTs be diagnosed?
cytology (can’t be graded this way)
How can MCTs be graded?
Histopathologically based on mittotic rate, degree of differentiation and tissue invasion.
What grade are most canine MCTs?
intermediate grade
Should MCT be considered as potentially malignant?
Yes
How should MCT staging be done?
- clinical and cytological exam of the regional LNs
- consider imaging the liver and spleen
- buffy coats and bone marrow aspirates are traditionally advised but it may be difficult to interpret.
Where do MCTs tend to metastasise?
- regional LNs
- liver
- spleen
- BM
T/F: some slow growing MCTs may transform into a more aggressive form
True
Tx - MCTs
- surgical excision (best in cases without LN involvement. Most low and intermediate grade tumours can be cured by good surgery. Intermediate grade tumours should be excised with a minimum of 2cm lateral margins and one deep facial plane. Examine histologically for completeness of excision)
- chemotherapy (give adjunctively if tumour is high grade)
- radiotherapy
Describe a papillomata
quite clinically striking
Describe sebaeceous adenomas
- spaniels
- older dogs
- look like warts but they are not
- biopsy –> straightforward histological diagnosis
T/F: cats are generally more likely to have malignant skin neoplasias than dogs
True
