O
Onchocerciasis
Etiology: Onchocerca volvulus (worm transmitted through bite of female blackfly)
Description: initially painless skin nodules that progressively become very itchy due to dead larvae; chronic itching leads to permanent skin color changes (leopard skin)
At risk: sub-Saharan Africa
Ass. sx: irreversible blindness (photophobia, eye itching, pain), epilepsy
Tx: oral ivermectin (1 does q3 mo to kill adult and larvae) +/- doxy
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Onycholysis
Etiology: idiopathic or secondary to trauma, skin disease, nail infections, tumors, or systemic event
Description: well-defined area of white opaque nail
Associated with: Psoriasis, Lichen Planus, Onychomycosis, Eczema
At risk: adult women
Tx: clip affected portion, keep nail short, minimize trauma, avoid irritants, antimicrobial soaks to prevent secondary infection
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Onychomycosis
Etiology: dermatophytes (75+% of cases), non-dermatophytes (aspergillum, candida, etc.)​
​At risk: 65+ yo, diabetic, immunocompromised, athletes​
Location: MC at 1st toe
​Tx:
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Mild = 50/50 soak in vinegar/water 3x/wk; topical nail polish thing
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Severe = oral terbinafine/griseofulvin
Osler nodes
Etiology: S. aureus (mostly), S. viridans (anything that can increase IC deposition)
Description: raised, violaceous lesions
Sx: "Osler nodes are Ouchy" = painful
Location: finger + toe pads
Tx: abx if underlying bacterial endocarditis, cutaneous lesions will resolve on own
