Thread by @vikrikon

📍Erythema 𝗺𝗮𝗿𝗴𝗶𝗻𝗮𝘁𝘂𝗺 vs
📍Erythema 𝗺𝗶𝗴𝗿𝗮𝗻𝘀 vs
📍Erythema 𝗶𝗻𝗳𝗲𝗰𝘁𝗶𝗼𝘀𝘂𝗺 vs
📍Erythema 𝗺𝘂𝗹𝘁𝗶𝗳𝗼𝗿𝗺𝗲 vs
📍Erythema 𝗻𝗼𝗱𝗼𝘀𝘂𝗺 vs
📍Erythema 𝗶𝗻𝗱𝘂𝗿𝗮𝘁𝘂𝗺

A short thread 🧵

𝗘.𝗺𝗮𝗿𝗴𝗶𝗻𝗮𝘁𝘂𝗺

Annular evanescent 𝗻𝗼𝗻-tender 𝗻𝗼𝗻-itchy macule with erythematous serpiginous border & central clearing
On trunk & extremities,𝗻𝗲𝘃𝗲𝗿 face

𝗖𝗮𝘂𝘀𝗲-Acute Rheumatic Fever(in ~6%)
also Psittacosis,Hereditary Angioedema

𝗘.𝗺𝗶𝗴𝗿𝗮𝗻𝘀

𝗘𝗮𝗿𝗹𝗶𝗲𝘀𝘁 skin finding of Lymes (in ~60%)

𝗠𝗼𝘀𝘁𝗹𝘆 a homogeneous erythematous eruption at tick bite site;3-30 days after bite & lasting weeks

Classic 𝗧𝗮𝗿𝗴𝗲𝘁 lesion in <10%-slowly expanding erythema with central clearing

𝗡𝗼 itch/warmth/pain

𝗘.𝗶𝗻𝗳𝗲𝗰𝘁𝗶𝗼𝘀𝘂𝗺
(5th disease/Slapped-cheek)

𝗣𝗮𝗿𝘃𝗼virus B19 in children

Erythematous malar rash of cheeks with circumferential oral pallor-𝗻𝗼𝘁 early in the disease process

At time of rash; viremia is resolved, patient is well and is 𝗻𝗼𝘁 infectious

𝗘.𝗺𝘂𝗹𝘁𝗶𝗳𝗼𝗿𝗺𝗲

Acute-onset acral(face,ears,extremities)
𝗧𝗮𝗿𝗴𝗲𝘁𝗼𝗶𝗱(3 zones)lesion
Central:Purpuric/dusky violaceous-may blister
Middle:Ring of pallor & edema
Outer: Erythema/blister

𝗖𝗮𝘂𝘀𝗲-Herpes & Mycoplasma mostly,
Other infections,vaccines,drugs

𝗘.𝗻𝗼𝗱𝗼𝘀𝘂𝗺-

Acute,nodular,erythematous eruption limited to the extensor aspects of lower legs-𝗻𝗼 ulceration, heals- 𝗻𝗼 scarring.

𝗖𝗮𝘂𝘀𝗲𝘀 - Infections, Inflammatory states, Drugs
MCC children- Streptococcus
MCC adult- Sarcoidosis

𝗛𝗶𝘀𝘁𝗼- Septal panniculitis

𝗘.𝗶𝗻𝗱𝘂𝗿𝗮𝘁𝘂𝗺 𝗼𝗳 𝗕𝗮𝘇𝗶𝗻

Chronic,nodular,erythematous-violaceous eruption on flexoral(posterior)aspect of lower legs:ulceration +- ,heal with scarring
[𝗟𝗲𝘀𝘀 tender,erythematous Cf. E.nodosum]

𝗖𝗮𝘂𝘀𝗲-𝗟𝗮𝘁𝗲𝗻𝘁 𝗧𝗕 in ~60%

𝗛𝗶𝘀𝘁𝗼:Lobular panniculitis