Diagnosing And Treating A Painful Tumor
Benign and bony outgrowths can be frequently misdiagnosed. With this mind, let us consider an unusual case involving a painful digital tumor that is gradually growing larger. Prior to presenting to our office, the patient had been evaluated by a couple of other physicians but the diagnosis had remained unclear.
The 19-year-old patient was an obese, non-diabetic female who had a chief complaint of a slowly enlarging painful tumor on the second left digit. She noted the lesion started approximately four months ago but recalled no trauma to this area.
The nodule, which had a reddish keratotic surface, projected out beyond the free edge of the distal border of the digit. The patient was referred to us by her internist after she had seen another DPM and a vascular specialist who referred her for two MRIs. None of the previous physicians made a diagnosis but the MRIs were read as osteomyelitis of the distal phanlanx.
What Is The Differential Diagnosis?
• Granuloma pyogenicum
• Glomus tumor
• Simple fibroma
• Subungual exostosis
Granuloma pyogenicum is very close clinically to the patient’s presentation. With these lesions, you will usually see a red, beefy soft tissue tumor. However, one usually sees these lesions interdigitally, plantarly or even at the proximal nail area. Another location for these lesions is in pin tract infections. The location alone should tell you this is not the correct diagnosis.
Glomus tumors are extremely painful. However, these tumors wouldn’t be clinically apparent as they are found underneath the nail. A simple fibroma is also incorrect as you wouldn’t see this lesion distally. Fibromas are more commonly found on the foot plantarly. While you don’t usually see malignancies on the tip of the toe, one would need to obtain a biopsy to rule this out completely.
Arriving At The Correct Diagnosis
Subungual exostosis is the correct answer. These lesions are benign, bony outgrowths that frequently masquerade, and are sometimes mistaken, for malignancy. An exostosis has been defined as a bony outgrowth from the surface of a bone.1 Exostoses growth is almost always on the margin, and usually on the inner margin, of the end of the last phalanx of the great toe.
Typical clinical signs of this condition are painful raised firm lesions that are located deep to the free edge of the nail. This growth pushes the nail edge and, sometimes, the entire nail upward. As a result, the patient may present with a “cutout shoe” or other modalities in order to help alleviate pressure from the shoe box.2 Pain is caused by the enlarging exostoses below and is exacerbated by the shoe pressure above. The loosened, raised nail plate is pathognmonic of this entity and should alert you to the appropriate diagnosis.
The causes of these lesions continue to be debated, but they are believed to be the result of trauma with or without superimposed infection.3 The patient may or may not recall a history of trauma.3 Keep in mind that the trauma may be caused by the confines of a nonforgiving, misfitted shoe. Historically, most of these lesions have been found on the halluxes, but lesions have been reported on the other toes and fingers.
Subungual exostoses develop more frequently during adolescence. The average age was 18 in 13 cases reported by William.4 In 42 cases reported by Kurtz, the ages varied from 6 to 50 with the majority of them appearing between the ages of 15 and 30.5
In addition to the patient history and clinical appearance of the condition, one should obtain radiographic imaging as well to confirm this diagnosis. Clinicians should pursue radiographic images on all raised digital tumors, with an emphasis on lateral or lateral oblique views as well as the dorsoplantar view.
Again, the differential diagnosis of subungual exostoses must include all those tumors that commonly occur in the subungual location. These include verrucae, granuloma pyogenicum, keratocathoma, melanotic whitlow, enchondroma, epidermal cyst, glomus tumor, epidermoid inclusions and subungual heloma. Of course, other lesions may occasionally appear subungually. These include hemangioma, angiokeratoma, sarcoid sarcoma, neurofibroma and malignancy.6,7