Introduction A painless, benign, slow-growing soft tissue tumor that often occurs in the hand occurs months to years after a traumatic event Epidemiology Incidence third most common hand tumor Demographics more common in men than women occurs in the third to fourth decade Anatomic location the distal phalanx is commonly involved Etiology Pathophysiology results from a penetrating injury that drives keratinizing epithelium into subcutaneous tissues or bone cells grow slowly to produce an epithelial cell-lined cyst filled with keratin Presentation Symptoms painless mass, most commonly occurring in the fingertip although less common, erythematous, painful lesions have been reported Physical exam inspection & palpation flesh-colored, yellow, or white in appearance well-circumscribed, firm, slightly mobile lesions login to view 1 more bullet often superficial and tethered to overlying skin range of motion there may be loss of ROM when lesions are large and occur near IP joints neurovascular exam sensory deficits may be evident with 2-point discrimination testing secondary to digital nerve compression Imaging Radiographs recommended views AP, lateral, and oblique views of the involved digit or hand findings soft tissue mass may be evident a lytic lesion of the distal phalanx may be present if the cyst erodes into bone login to view 1 more bullet Studies Biopsy indications should be considered before surgical excision to rule out neoplasm or infection if a lytic bony lesion is present in the distal phalanx Histology gross appearance cysts contain a thick, white keratinous material characteristic findings cysts filled with keratin and lined with epithelial cells Differential Tophaceous gout Foreign body granuloma Sebaceous cyst Pyogenic granuloma Giant cell tumor Ganglion cyst Enchondroma Glomus tumor Treatment Nonoperative observation indications login to view 1 more bullet Operative marginal excision indications login to view 4 more bullets technique login to view 3 more bullets outcomes login to view 2 more bullets Complications Wound complications Infection Digital neurapraxia Recurrence recurrence rate is low even with bony involvement Prognosis Excision is curative Malignant transformation has not been reported