"Knarley" Knuckles in a 12-year-old Boy

A 12-year-old boy complains of asymptomatic swellings over his “knuckles” (actually over the proximal interphalangeal joints) that he has had “all my life.”

PMH noncontributory; no family hisotry; patient denies: trauma, finger sucking, etc; no joint swelling, photo-intolerance.

Physical examination: Firm, flesh-colored pads over the proximal (IP) joints of both thumbs and fingers. no evidence of keloids; no obvious joint contractures.

Do you have a differential diagnosis in mind?

A partial differential diagnosis: Calluses, fibromas, foreign body reactions, gouty tophi, dermatomyositis, knuckle pads, Heberden nodules, pachydermodactyly, warts, rheumatoid nodules, granuloma annulare, self-induced trauma.

The diagnosis is: F. Knuckle pads: well defined thickenings over the IP joints (usually proximal IP vs other); classified as a form of fibromatosis

Knuckle pads have been identified in Renaissance paintings and Michelangelo’s famous statues of David (in Florence) and Moses (in Rome).

Knuckle pads may be autosomal dominant or secondary to trauma; can be occupational; within families age of onset typically after age 30 y. May affect single or multiple joints; hands most commonly affected.

Knuckle pads, facts: No predilection for age, sex; no yeild from lab test.Keratolytic agents have softened some lesions.

Knuckle pads, additional differential: Scars/keloid, epidermolysis bullosa acquisita, epidermolysis bullosa dystrophica, digital fibroma, xanthomas, erythropoetic protoporphyria

When patient and mother learned knuckle pads are benign, they were relieved. Always helpful to take photos and keep them on hand for the next time you see something similar.