Age / Sex : 34 / M

Chief complaint: painful mass

What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(Please submit only one answer)

Courtesy: Hee Jin Park, Kangbuk Samsung hospital

Intraosseous epidermoid cyst

Discussion

most common in adults, especially manual workers

males are more frequently affected

fourth or fifth decade of life (range 8 to 83 years).

 The distal phalanx is most commonly affected

Also other phalanges.

thumb, then the middle finger, and least commonly the little finger.

Rarely digits of the feet may be affected.

In over 45% of the cases, there is a history of minor or major blunt or penetrating trauma (frequently a crush injury)

may have occurred many years prior to presentation

may result from implantation of epithelial cells into the subcutaneous tissues as a result of trauma.

Surviving cells would subsequently proliferate and produce keratin

absence of trauma, proliferation of intraosseous inclusions of epithelial elements during embryogenesis

well-defined osteolytic lesion without any trabecular pattern.

may be cortical thinning or erosion.

typically bony sclerosis or reaction is absent.

MR

T1 – predominatly iso

T2 – variable from debri.

Low – keratin, High – cholesterol

T1Gd – enhancing capsule