Nodular skin disease Flashcards
Define what a nodule is
A circumscribed solid elevation greater than 1 cm in diameter that usually extends into deeper layers of skin
Nodules usually result from infiltration of?
- Inflammatory cells
- Neoplastic cells
- Deposition of fibrin or crystals (e.g. calcinosis cutis)
What factors need to be considered when a nodule is clinically presented?
- Location on the body
- Number (single vs multiple)
- Size
- Behaviour (acute vs gradual onset)
- Aspect/clinical features
Give some examples of nodule clinical features
- Warm and/or painful
- Hard, soft, elastic, fluctuant, movable, fixed
- Alopecic, smooth/rough surface
- Ulcerated: possible presence of draining tracts
- Hyper/hypopigmented
Describe cytology of a nodule
- Fine needle aspirate
- Apposition (if ulcerated/discharging)
- Can be diagnostic or direct you to further testing (culture, special stains, immunocytochemistry)
Describe histology of a nodule
- Excision of the whole nodule
- Punch/wedge biopsy
- Depends on clinical presentation (number, size, location)
- Often diagnostic (especially when single nodules are excised and when dealing with neoplastic conditions)
What further diagnostic tests can be taken when dealing with nodules?
- Immunohistochemistry, clonality
- Special stains (Gram, PAS, ZN, GMS)
- PCR
- Biochemistry, urinalysis (e.g. calcinosis cutis)
- Serology (e.g. Leishmania, Toxoplasma, Neospora, Cryptococcus)
Give some examples of things that may cause a nodule due to a foreign body reaction
- Plant material
- Grass
- Embedded insect mouth parts
- Suture material
- Endogenous material e.g. hair, sebum, keratin
What are 3 causes of abscesses?
- Penetrating wounds
- Bites
- Foreign bodies
What clinical signs are caused by filamentous bacteria?
- Nodules and abscesses, with ulcers, draining tracts and cellulitis -> anywhere the bacteria are inoculated (mainly extremities, head and neck, and inguinal area) from bite wounds or penetrating foreign bodies
- Serosanguineous exudate
- Possible systemic signs – pyrexia, depression
How are filamentous bacteria diagnosed?
- Cytology +/- special stains (Gram, ZN)
- Histology +/- special stains - nodular to diffuse pyogranulomatous dermatitis and panniculitis, with or without tissue grains “sulfur granules”
- Culture
How are filamentous bacteria treated?
Surgical drainage and antimicrobial therapy
Mycobacteria (saprophytic) cause which two conditions? Which animals does each affect?
Canine leproid granuloma (CLG) – short coated breed (boxers ++)
Feline leprosy syndromes (FLS) - ++ male cats with outdoor access
What are the clinical signs of a patient infected with mycobacteria (saprophytic)?
- Single or multiple, firm, well‐circumscribed nodules in the skin or subcutis
- Peripheral lymphadenomegaly
How is mycobacteria (saprophytic) diagnosed?
- Cytology + special stains
- Histology + special stains
- Culture: specialist mycobacterial culture and subsequent genotyping at a national reference laboratory (APHA) for official confirmation
Atypical/non-tuberculous mycobacteria can affect which SA species?
Cats
What are the signs of Atypical/non-tuberculous mycobacteria?
Granulomatous panniculitis - Single/multiple nodules, plaques, macules and diffuse swelling – multiple punctate ulcers and draining tracts (++ inguinal fat pad, tail base, flank)
What are the clinical signs of mycobacterium tuberculosis in small animals?
- ++ Male outdoor cats – face, extremities, tail base, perineum
- Firm nodules, ulcerations, non-healing wounds with draining tracts -> thick yellow to green fluid + systemic signs
- +/- local or generalized lymphadenopathy
How is mycobacterium tuberculosis in small animals treated?
Notifiable disease – owner might need to be screened at TB-clinic
Euthanasia/empirical multidrug regimens/culture and susceptibility
Dermatophytic pseudomycetoma causes what clinical signs?
- Commonly Persian or domestic long hair cats
- Painless, single or multifocal ulcerated dermal nodules - yellow granular discharge
- NO history of skin trauma
- Neck, dorsum, tail, flanks or limbs
How is Dermatophytic pseudomycetoma treated?
Systemic antifungals (itraconazole, ketoconazole, terbinafine) +/- surgery
Describe the clinical signs of nodular dermatophytosis (dogs)
- Single ++ or multiple erythematous, alopecic, exudative nodules
- Head, neck, limbs
Name some examples of subcutaneous fungal infection
- Mycetomas
- Chronomycosis
- Hyalohyphomycosis
- Cryptomycosis
Name 3 examples of protozoa that can cause nodular skin lesions (this is rare)
- Toxoplasma gondii
- Neospora caninum
- Leishmania spp
Name 3 examples of immune mediated conditions that can cause nodular skin lesions
- (Juvenile) Sterile granulomatous dermatitis
- Eosinophilic granuloma
- Sterile Pyogranulomatous Dermatitis
Name some neoplastic histiocytic proliferative disorders
- Histiocytomas
- Canine cutaneous Langerhans cell histiocytosis
- Histiocytic sarcoma
- Feline progressive histiocytosis
Cutaneous histiocytosis is an example of what kind of disorder?
Reactive histiocytic proliferative disorders
Describe the main features of Cutaneous histiocytosis
- Inflammatory lymphohistiocytic proliferative disorder that primarily involves skin and subcutis
- Multiple cutaneous and subcutaneous nodules up to 4 cm diameter – non-painful, non-pruritic
- Skin ulceration common
How are histiocytic proliferative disorders treated?
Glucocorticoids
Ciclosporin
