William F. Keenan, MD

This lesion looks suspiciously like a malignant melanoma.

A 56-year-old man, who had a history of cigarette smoking, noticed a sudden swelling in his neck, mainly on the right side. Shortly thereafter, his right arm became enlarged.

The 83-year-old woman whose hands are shown in photograph A had a severe flare of arthritis in the metacarpophalangeal and proximal interphalangeal (PIP) joints after corticosteroid therapy for her asthma was stopped. The clue to the diagnosis of psoriatic arthritis is in her fingernails, which show both pitting and onycholysis.

This young boy complained of itchy lesions after he spent a day in a semiwooded area. The lesions appear urticarial, but note that the pattern of eruption is over areas of constrictive clothing: the arm of a shirt and the belt.

Several hours after returning from a walk in tall grass, a 9-year-old boy began to complain about intense itching around his waist, lower back, and upper arms. Wheals developed on these areas.

The characteristic marking of the true brown recluse spider is an upside-down violin shape on the dorsal cephalothorax.

A 67-year-old woman presented with a painful genital ulcer. She denied new sex partners and previous genital lesions.

Abrupt onset of symmetric inflammatory arthritis and edema, as seen on the dorsum of this 72-year-old man's hand, is characteristic of remitting seronegative symmetric synovitis with pitting edema-or RS3PE. The work-up of this patient was essentially negative for other types of inflammatory arthritides.

A 67-year-old woman presented with a painful genital ulcer. She denied new sex partners and previous genital lesions.