Subungual Extraosseous Chondroma in a Finger

Abstract not available. Introduction provided instead.

Chondromas are benign cartilage-producing tumors that are commonly found in tubular bones but seldom form in extraosseous soft tissues. These tumors must be distinguished from their malignant counterparts by histology and biological behavior. The 3 types of extraosseous chondromas are intra-articular/para- articular chondromas, juxtacortical chondromas, and chondromas of soft parts. Intra-articular/para-articular chondromas are histologically different in that they include benign-appearing nuclei.¹ Juxtacortical chondromas and chondromas of soft parts tend to have mild nuclear atypia, despite a benign clinical course, and differ only in their association with periosteum and synovium, respectively.^2-9 Juxtacortical chondromas are adjacent to bone and subperiosteum, whereas chondromas of soft parts are found in various tissue planes often associated with synovium.

Here we report the case of a rare subungual extraosseous chondroma that presented atypically and that was therefore treated aggressively with disarticulation, despite an ultimately benign pathologic evaluation. The subungual location caused the tumor to obliterate the overlying nail bed and nail plate, raising concern of a potentially malignant pathology during initial evaluation. In addition, the elderly male patient’s tumor was near the distal interphalangeal (DIP) joint. Disarticulation was planned before surgery not only because of potential malignancy but also because of location. Resection followed by reconstruction of the nondominant, index finger distal phalanx would have required a more complex procedure, such as a skin graft or a crossfinger flap, without a significantly improved functional outcome. These options necessitate more surgery with the morbidity of a donor site and a return to the operating room for pedicle division in the finger-flap option. These options went against the patient’s wish for minimal surgery. In this patient, the paucity of subungual soft tissue caused the tumor to appear in a juxtacortical location, though it actually sat in a supraperiosteal tissue plane. As a result, the tumor was found in close opposition to the underlying bone but lacked the classic radiologic findings of juxtacortical chondromas, such as bony saucerization and sclerosis.^8,9 Having a better understanding of the nature of juxtacortical chondromas and chondromas of soft parts should aid surgeons in anticipating the diagnosis in the instance of atypical presentation and should help make them more comfortable managing treatment decisions surrounding these histologically worrisome, yet benign lesions.