Chondromas are benign cartilage-producing tumors, commonly found in tubular bones but rarely form in extraosseous soft tissues. They must be differentiated from their malignant counterparts by histology and biological behavior. 

A report describes a case of a right-handed man who was in his mid-70s. He presented with a painless, slow-growing tumor within the distal phalanx of the left index finger, which was first noted after trauma to the finger 9 years before presentation. No history of medical treatment during the intervening years was reported. He gave a medical history of seizure disorder treated with lamotrigine, hypertension treated with metoprolol and hypercholesterolemia treated with simvastatin. He denied smoking. 

Physical examination exposed a 1×1cm mass on the dorsum of the distal phalanx of the left index finger. No nail or residual nail bed was evident. The tumor was examined to be round, white, hard, and smooth without any evidence of inflammation. He demonstrated a full painless range of motion of the distal interphalangeal (DIP) joint. The hand examination was otherwise unremarkable. Radiographs revealed a small indentation in the dorsum of the distal phalanx with little reactive sclerosis and no evidence of bony invasion. No scalloping of the bone and no stippling or other soft-tissue irregularity was found. 

The patient agreed to excision and disarticulation of the DIP joint, as the diagnosis was not definite, and, though the prolonged clinical course suggested the lesion was benign, complete obliteration of the nail bed could symbolize malignant progression. The classic radiographic signs of juxtacorticalchondromas, cortical erosion and overhanging reactive sclerosis were missing, and no visible calcified masses to indicate one of the other possible benign subungual hard-tissue masses was present. 

Furthermore, the patient requested limited surgery without the need for complex reconstruction to preserve the tip of the finger. Disarticulation was performed during surgery, as the tumor could not be removed with safe margins. The distal phalanx/tumor was removed en bloc and the patient healed uneventfully. 

Histopathology revealed no erosion or induction of sclerosis of the contiguous cortex. The tumor was seen separated from the cortex by a periosteal fibrous membrane, while the other surface was covered with skin. The neoplasm comprised of mature adult hyaline cartilage arranged in a lobular manner was seen. Very few cartilage cells containing double nuclei were seen. No calcifications were seen. 

The lesion was initially diagnosed as juxtacorticalchondroma, but after reviewing the literature and noticing the location of the tumor in a tissue plane superficial to the periosteum, the diagnosis of chondroma of soft parts was made. 

Source: Rottgers SA, Rao G, Wollstein R. subungual extraosseouschondroma in a finger. Am J Orthop(Belle Mead NJ). 2008;37(11):E187-90.