Prominent scaly fixed erythema, flat or raised over malar eminences, tending to spare nasolabial folds (“butterfly rash”).

Sclerodactyly showing bilateral swelling, a shiny wax-like appearance, and tapering of the fingers. May also note digital ulcers, nailfold telangiectasia, and periarticular calcinosis. Flexion contractures present in advanced disease. (Courtesy Dr. A. Fam)

Note subluxation of digits at the metacarpophalangeal (MCP) joints and rheumatoid nodules at 2nd and 3rd MCPs. (Courtesy of Dr. D. Jerome)

Significant ulnar deviation of the digits, typical of rheumatoid arthritis.

Note white discolouration of digits. (Courtesy of Dr. D. Jerome)

Onycholysis: Lifting of the nail starting at the distal end, seen in psoriatic arthritis. (Courtesy of Dr. D. Jerome)

Nail pitting seen in psoriatic arthritis. (Courtesy of Dr. D. Jerome)

Violaceous, hyperpigmented, atrophic plaques; keratotic scale with follicular plugging and scarring. (Courtesy Dr. L. From)

Classic heliotrope rash of periorbital and perinasal violaceous erythema. (Courtesy Dr. M. Urowitz)

Dermatomyositis (DM) of Hands
Erythematous flat-topped scaling papules over the knuckles showing Gottron’s papules and periungal telangiectasia. (Courtesy of The Hospital for Sick Children Slide Library, Toronto)

Acute Pseudogout (Calcium Pyrophosphate Dihydrate Crystals)
Polarized light microscopy showing calcium pyrophosphate dihydrate crystals. Note the positive bifringence (blue) of rhomboid-shaped crystals versus the needle-shaped and negatively birefringent (yellow) crystals of gout. (Courtesy of Dr. A. Fam)

Acute Gout (Monosodium Urate Crystals)
Polarized light microscopy showing monosodium urate crystals. Note the negative birefringence (yellow) of needle-shaped crystals versus the rhomboid-shaped and positively birefringent (blue) crystals of crystal pyrophosphate disease (CPPD). (Courtesy Dr. A. Fam)

Acute Gouty Arthritis
Classic inflammation resembling cellulitis of the first metatarsophalangeal (MTP) joint, referred to as podagra. The first MTP is the most common site of initial involvement. (Courtesy Dr. A. Fam)

Ring and long digit radiograph in a patient with psoriatic arthritis. There is loss of the tuft to the ring finger (arrow), so called acroosteolysis. The long finger shows soft tissue swelling (asterisk) with severe joint space loss and erosions at the proximal interphalangeal (PIP) joint. The bone density is increased involving the proximal and middle phalanx to the long finger (ivory phalanx) related to periostitis, a characteristic feature of psoriatic arthritis. (Courtesy of Dr. A. Donovan)

Right foot radiograph in a patient with psoriatic arthritis. There is pencil-in-cup deformity involving the proximal interphalangeal (PIP) joint to the third toe (arrow). (Courtesy of Dr. A. Donovan)

Left long finger radiograph in a patient with psoriatic arthritis and dactylitis. Note soft tissue swelling at the proximal interphalangeal (PIP) joint. Arrows show proliferative new bone formation. There is moderate joint space loss at the PIP joint. (Courtesy of Dr. A. Donovan)

Left hand radiograph in a patient with rheumatoid arthritis shows extensive erosions at the distal radius, ulna, and carpus. Erosive changes are also seen at metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints. (Courtesy of Dr. A. Donovan)

Right hand radiograph in a patient with advanced rheumatoid arthritis with erosions of the distal radius and ulnar styloid, as well as severe joint space loss with erosions throughout the carpus with soft tissue swelling. (Courtesy of Dr. A. Donovan)

Right hand radiograph in a patient with advanced rheumatoid arthritis. There are extensive marginal erosions and ulnar subluxations at the metacarpophalangeal (MCP) joints. Erosions are also present at PIP joints. (Courtesy of Dr. A. Donovan)

Right wrist radiograph in a patient with rheumatoid arthritis. The arrows show erosions at the ulnar styloid and distal radius. Asterisk shows additional erosions at the carpus. (Courtesy of Dr. A. Donovan)

Left hip joint radiograph shows severe superior joint space narrowing, subchondral cysts, subchondral sclerosis and marginal osteophytes. These are radiographic hallmarks of osteoarthritis. (Courtesy of Dr. A. Donovan)

Bilateral hands in a patient with lupus. Note finger flexion and extension deformities in the absence of erosions. (Courtesy of Dr. A. Donovan)

Right wrist radiograph shows chondrocalcinosis involving the triangular fibrocartilage complex (arrow). (Courtesy of Dr. A. Donovan)

Note purpuric papules. (Courtesy Dr. A. Fam)