Lumps and Bumps- Nodules Flashcards
1
Q
define a nodule
A
circumscribed skin elevation >1cm
pleomorphic: can range from hair covered, normal looking skin, crusty, angry, ulcerative, etc.
-can affect any body part, including the toes
2
Q
what situations can cause skin nodules?
A
- inflammation:
-infectious: bacteria, fungi, oomycetes, parasites
-sterile - neoplasia
- foreign material
-exogenous: licking one paw for several months
-endogenous
3
Q
give an example of exogenous foreign material causing a nodule
A
licking one paw for several months, interdigital nodule develops slowly
or foreign body: any dermal foreign body (plant material, wood, metal, glass, etc.) can cause nodular skin lesions, often with draining tracts
-ALSO any plant material can have soil (saprophytic fungal infections possible)
4
Q
what are the main tools for nodular lesions?
A
- history and clinical presentation
- cytology of exudate
- FNA
- biopsy
- culture: swabs from exudate, tissue cultures)
-careful though because the skin ALWAYS has a microbiome - PCR
- sequencing
5
Q
describe bacterial furunculosis
A
complication of superficial pyoderma
- inflammation breaks through the hair follicle wall
- hair, keratin, bacteria, inflammatory cells, and parasites enter the dermis
- dermis responds with severe inflammation (nodule formation) and HEMORRHAGE
- folliculitis vs furunculosis
-folliculitis: hair follicle intact, disease process confined to hair follicle
-furunculitis: hair follicle exploded, wall no longer intact, results in dermal hemorrhage (red-blue color), and foreign body reaction to hair and keratin - 3 most common etiologies in folliculitis:
-staphylococcal infection!! (pseudintermedius most common in dogs!can isolate aureus if swapping skin with a human)
-dermatophyte infection
-demodex mite infestation
-can all progress to furunculosis!
-plus: pseudomonas aeruginosa can also
6
Q
describe what is commonly seen on histopathology of bacterial furunculosis
A
- ruptured hair follicle, free floating keratin in dermis
- inflammation and hemorrhage can be very intense and bacteria may not be readily visible without special stains
7
Q
describe specific types of bacterial furunculosis
A
- canine interdigital furunculosis:
-most commonly due to/secondary to atopic dermatitis
-problematic because walking hurts and friction from walking impedes healing - feline furunculosis and cellulitis: often secondary to initial cat bite
- canine chin furunculosis: secondary to atopic dermatitis
8
Q
describe feline acne
A
- initially comedones (black heads)
- can progress to pustules (folliculitis)
- then to furunculosis
+/- draining tracts, tissue swelling, pain, pruritis - many have concurrent atopic dermatitis
9
Q
describe canine acral lick dermatitis (lick granuloma)
A
- created by incessant licking behavior and subsequent infection
- most commonly affected lower limbs in canine patients
- etiology can be very complex and multifactorial
-atopic dermatitis
-bacterial infections
-flea allergy dermatitis
-orthopedic disorders
-neurologic disorders
-fungal infections
-neoplasia (mast cell tumor)
-psychogenic disorders (separation anxiety) - treatment requires thorough history taking to determine cause
10
Q
describe treatment of bacterial furunculosis
A
- topical:
-antibacterial shampoo (good but limited time exposure), spray, ointment, cream, gel, mousse
-choose/try topical whenever you can! - systemic:
-antibiotics
-similar to superficial pyoderma treatment but given longer
-treat for >6 weeks then 3 weeks beyond remission
-bacterial culture and antibiotic sensitivity testing if no improvement
11
Q
how can patients get skin infections from flora that are part of their normal skin microbiome?
A
- allergies: to fleas, environmental allergens, food allergens, causes inflammation that impacts the microbiome which starts to shift toward infection
- parasites
- skin trauma
- hormonal imbalances: hypothyroidism, hyperadrenocorticism
-even if culture a bacteria, the body can react by walling off the bacteria (botryomycosis, splendore-hoeppli reaction) and requires surgical resection
12
Q
what fungal infections can cause skin nodules?
A
- dermatophytosis: usually superficial lesions, but every now and then can invade deeper into dermis and make nodule
-so if see a cat with nodules, CAN’T rule out dermatophytosis
-microsporum canis (cats)
-mirosporum gypseum (infected soil; digging dogs can pick up)
-trichophyton mentagrophytes (infected rodents, can infect cattle)
-ZOONOTIC - saprophytic (soil-living) fungal infection:
-usually require skin break and implantation into dermis to establish infection but not zoonotic
-hyalophyomycoses (non-pigmented fungi)
-phaehyphomycoses (pigmented fungi) - systemic fungal infections:
-blastomycosis, cryptococcosis, sporotrichosis, histoplasmosis
-often also systemically sick!!
13
Q
describe equine mucormycosis
A
- unpredictable antifungal susceptibility pattern of over 40 different fungal species
- surgical resection of infected tissue is often indicated (but not always possible)
-followed by antifungal treatment for long periods of time (up to several months)
14
Q
describe pythiosis insidiosum
A
- also called swamp cancer or water mold infection; a fungus-like aquatic organism
- motile zoospores released into water enter the skin via small pre-existing wounds
-cause tissue infection - usually starts as a small nodular lesion
-often slow progression - typically no response to treatment
-fungal cell wall is chitin, but oomycete cell wall is cellulose so traditional antifungals rarely work well
-RADICAL surgical resection of infected tissue is treatment of choice (amputation); may not always be possible - histopathology:
-pygranulomatous dermatitis/panniculitis with eosinophils and intralesional fungal hyphae
-but histopath CANNOT provide a final diagnosis; tissue culture and/or PCR are necessary
15
Q
describe demodex canis
A
can cause furunculosis, we are currently unsure why they sometimes over reproduce (not observed in all dogs on immunosuppression)
16
Q
describe equine summer sores
A
- nodular, ulcerative and hemorrhagic skin lesions which may have small sulfur grains (calcified tissue concretions)
- histopathology reveal larvae of:
-habronema spp.
-draschia spp.
-and intense inflammation - cutaneous habronemiasis: caused by larvae of nematode stomach worms
-habronema muscae
-habronema microstoma
-draschia megastoma - life cycle:
-eggs and L1 larvae shed in horse feces
-flies eat poop and larvae
-flies feed on horses (eyes, mouth, genitals)
-L3 larvae ingested by horse and head to the stomach and produces more eggs
-but the flies who go to the eyes and the genitals drop larvae that don’t get swallowed, so larvae dig into skin for protection, now in wrong habitat and skin has massive inflammatory response; larvae cannot develop and eventually die
-will resolve on own if gets cold as body can heal (summer sores) - diagnosis is based on history and histopathology
-lesions range from mild to severe - treatment:
-fly prevention and manure removal
-deworming
-systemic and topical steroids
-antiseptics/antibiotics if indicated
17
Q
describe feline eosinophilic granulomas (sterile inflammation)
A
- chronic inflammatory condition often linked to feline allergic skin syndrome (FASS)
-underlying cause remains unknown - can affect various body areas including oral cavity
-lesions may ulcerate and may or may not be pruritic
-oral cavity lesions can cause difficulty eating or swallowing
18
Q
describe equine eosinophilic granulomas (sterile inflammation)
A
- most common nodular skin disease of horses!!
- etiology is unclear but a reaction to insect bites is suspected (or trauma or allergy related)
- vary in size from 0.5-5cm
-single to hundreds of lesions
-non-pruritic - may wax and wane seasonally
19
Q
describe canine facial eosinophilic furunculosis (sterile inflammation)
A
- hyperacute onset
- usually starts on bridge of nose
-rapid progression to muzzle, face, and periocular regions - cytology shows large amounts of eosinophils
-may see bacteria in cytology as well - insect bites are suspected as a trigger
- lesions are responsive to steroids but hair may not grow back if wiped out by inflammation
20
Q
describe canine juvenile cellulitis/puppy strangles (sterile inflammation)
A
- uncommon and idiopathic wth acute/rapid onset
- . primarily in puppies
-3 weeks to 6 months old - staphylococcus intermedius is usually present but role is unknown
- erythematous tissue swellings around eyes, nose, and lips
-pustules, papules, nodules, crusts, ulceration
-severely enlarged mandibular lymph nodes, fever, lethargy, inappetance - diagnosis based on history, clinical signs, +/-cytology and histopathology
- treatment:
-systemic steroids ASAP
-supportive care
-cleaning
-topical antiseptics if indicated
21
Q
describe sterile pyogranulomatous dermatitis and panniculitis (sterile inflammation)
A
- uncommon to rare in dogs, very rare in cats
-no age, sex, breed predilection - often acute onset but can become chronic
- single to widespread lesions
-systemic signs may be present: fever, depression, anorexia
-diagnosis by rule out/exclusion - no current evidence for true triggers, but have debated drug reactions and previous infections followed by an aberrant patient immune response
- histopathology:
-neutrophils and macrophages invading panniculus and deep dermis
-no microbes upon special stains
-tissue cultures negative
-usually have to make a call right after biopsy or even FNA (tissue cultures take time) - response to immunosuppressive treatment with steroids is fast but other non-steroidal immunomodulatory drugs (like cyclosporine) are added since treatment often longterm (months)
-decision to treat: acute widespread onset is hallmark of sterile immune mediated disease (IMPORTANT) - complications (rare, most recover and don’t relapse)
-complications are really only the result of lack of treatment or inappropriate treatment
-lesions are very deep so will have scars when heal
22
Q
describe follicular cysts (endogenous foreign material)
A
- follicles filled with keratin
- huge size range
- rupture into dermis causes foreign material
- treatment:
-benign neglect
-drainage and cyst lining removal via small surgical incision
-complete surgical removal
23
Q
describe dermal calcinosis (endogenous foreign material)
A
- may develop with hyperadrenocorticism or long term steroid use
-lead to slow development and slow spread of nodular, crusty skin lesions on dorsum - why not everyone develop? we dont know
- histopathology: dermal calcinosis (dark pink granular material)
- treatment:
-address underlying cause
-topical antiseptics
-hydrotherapy
