Subungual exostosis: treatment as an office procedure

Subungual Exostosis of the Hand: A Case Report in a 5-Year-Old Boy and Literature Review

Subungual exostosis is a relatively uncommon benign tumor that occurs at the distal end of the distal phalanx of the toes and rarely the hands. We present in this article a review of the currently published English literature and provide a case report of a 5 year old male with subungual exostosis of the thumb.

A 5 year old male presented with a slow growing mass of the distal dorsal aspect of the left thumb. Radiographs showed dorsal calcifications on the thumb. Surgical removal of the mass and histopathological analysis was performed supporting a diagnosis of subungual exostosis. Post-operatively, the patient had complete excision of the mass, normal nail morphology, no reoccurrence, and no post-surgical complications.

Subungual exostosis remains a rare entity especially in the upper extremity. Its cause is not fully understood, nor is there an agreed upon method of treatment. However, with careful dissection during surgical removal good outcomes can be obtained. To our knowledge, this is the largest literature review on subungual exostosis and our case report is an uncommon presentation in the youngest reported male patient. It is our hope that this literature review and case report lend to increased awareness of subungual exostosis and how to diagnose and treat this lesion.

Subungual Exostosis Systematic Review and Meta-Analysis

BACKGROUND

The coexistence of deformity of the nail bed and subungual exostosis (SE) is a frequent finding in podiatric practice in the fourth and fifth decades of life. However, it has been described by other specialists as being an uncommon osteocartilaginous tumor most prevalent during the second and third decades of life. This study attempts to determine the causes of this discrepancy.

METHODS

Two authors independently conducted a systematic bibliographic review in multiple databases, podiatry sources and others, and key words were chosen to achieve a broad search strategy. Studies reporting on epidemiology and treatment of SE lesions in lower extremities in ten or more patients were selected. Initially, 197 articles were identified through database screening, with 23 meeting all inclusion and exclusion criteria. Seven articles with the ages of all of the patients were included in the analysis of age data. A comparison was then made between the diagnostic criteria for the selected 23 articles.

RESULTS

Model results reveal that, although there are some significant differences between individual studies, the main factor tested (patient's age) was clearly significant ( F_1,5.2 = 78.12, P < .001), showing that studies coming from the podiatry speciality were conducted on individuals with a mean age of 37 years higher than in studies from other specialties. Clinical and radiologic characteristics and treatment described in the podiatry literature also contrast with those in other specialties.

CONCLUSIONS

The SE described by podiatrists, in accordance with the parameters of true exostosis, is different from Dupuytren's SE and should be considered as a different pathologic entity. The authors are working on its histologic identification.

Subungual exostosis of the toes: a systematic review

BACKGROUND

Subungual exostosis is a relatively common benign bone tumor that occurs in the distal phalanges of the toes and can be a source of pain and nail deformity. There is controversy about the treatment of these lesions and there are few studies that have synthesized what is known and provided meaningful information on treatment.

QUESTIONS/PURPOSES

We performed a systematic review to address the following questions: (1) What is the best surgical approach for excising these lesions? (2) What is the age range, sex distribution, and presenting symptoms of subungual exostoses and which toe is most frequently affected? (3) What complications arise from treatment?

METHODS

Two authors independently searched multiple databases (Medline, 1950-May 2013; Cochrane EBM database, and EMBASE, 1980-May 2013 provided by OVID; ACP Journal Club, 2003-May 2013; CINAHL by EBSCO, 1937-May 2013; and PubMed by NLM, 1940-May 2013), and key words were chosen to achieve a broad search strategy. We included studies on the management of toe exostoses with > 10 cases and we excluded studies that reported on upper extremity exostoses or osteochondromas. Demographic and treatment data were collected from each article by two independent authors and collated. A total of 124 abstracts were screened, and 116 articles were reviewed in full, of which 13 met the inclusion criteria.

RESULTS

Complete marginal excision through a fish mouth incision protecting the nail led to a recurrence rate of 4% and satisfactory clinical results, defined as no requirement for postoperative intervention and a satisfactory clinical appearance in 73%. Most studies provided incomplete descriptions of specific surgical techniques used. Fifty-five percent of the patients were younger than 18 years of age. A history of toe trauma before diagnosis was present in approximately 30% of the cases. Delayed diagnosis occurred in approximately 10% of the cases and onychodystrophy occurred in more than 10%.

CONCLUSIONS

There is weak evidence to guide management of subungual exostosis. Adequate wound management postexcision aiming to minimize disruption to the nail bed and matrix may prevent onychodystrophy, which is a common complication of treatment.

Subungual exostosis of the great toe: a case report and tumor overview

Subungual exostosis is an acquired, benign, and solitary bone tumor of the distal phalanx occurring beneath or adjacent to nail. A 18-year-old man presented with a lump, ulceration, and pain on his right big toe. This complaint was present for the past 2 years. Initially, lump and pain were present, and since the past 6 months ulceration and superadded infection occurred. Plain radiograph showed a calcified lesion that was continuous with the phalangeal cortical surface in the distal dorsal aspect of the big toe. Excisional biopsy with complete nail removal and reconstruction of the tip of the toe were done. Histopathology confirmed the diagnosis of subungual exostosis. Clinical or radiological recurrence was not observed after 26 months of follow-up. The case is reported to present the tumor overview and to highlight that the diagnosis of this benign lesion should not be missed. Clinical and radiological features allow early diagnosis and treatment thus preventing the lesion to progress to the stage of onycholysis.

LEVEL OF EVIDENCE

Therapeutic, Level IV.

Treatment of subungual exostoses by elective day case surgery

Twenty-one patients (11 female, 10 male: mean age 21.3 years) with subungual exostoses were treated with elective surgery under local anaesthetic in a dermatology day case theatre over a period of 8 years. Fifteen (71%) tumours affected the great toe, four (19%) affected other toes and two (10%) affected fingers. All received local excision with great care to remove all tumour residue from the terminal phalanx. Wounds were allowed to heal by secondary intention. Attention was paid to preoperative antiseptic procedure and postoperative analgesia. During follow-up of between 6 and 36 months (mean 17 months), there were two relapses (10%) in the first 12 months, seen in two of the younger subjects aged 9 and 13 years. One required further surgery. One further case suffered long-term dystrophy due to perioperative damage to nail matrix. Conservative and thorough treatment of this pathology can be achieved using the appropriate tools in a dermatology day case theatre.

Subungual exostosis: diagnosis and treatment in children

Subungual exostosis is a benign bone tumor of the distal phalanx occurring beneath or adjacent to the nail. The exostosis occurs most commonly in the toes, most frequently involving the distal phalanx of the hallux. The majority of the lesions occur in the second or third decade of life. From 1975 to 1995, 21 children were treated for subungual exostosis at the Children's Hospital of Eastern Ontario, 20 of whom underwent local excision. One patient required an amputation of the affected distal phalanx due to recurrence of the lesion. The subungual exostosis occurred on the hallux in 14 children, the second toe in three children, the third toe in two children, and the fourth toe in two children. No lesion was encountered in the little toe. The exostosis is very rare in patients under 7 years of age; the average age in this review being 12 years and 6 months. The lesion recurred in three children. Removal of the nail over the exostosis facilitates the mandatory entire removal of the lesion.

Subungual exostosis of the foot

Eleven subungual exostoses of the foot (10 on the hallux, 1 on the third toe) were studied. The initial symptom was subungual pain. When a subungual mass of fibrous tissue appeared, the nail was pushed up and in one case the mass became infected. X-rays exhibited a bone mass protruding from the terminal phalanx on the dorsomedial aspect of the toe in all cases. All patients underwent surgical excision of the lesions with partial onychectomy. Three layers were identified in five cases: a cap of fibrous tissue, a middle zone of hyaline cartilage with enchondral ossification, and a deep zone of cancellous bone. In three other cases, the histological pattern was pleomorphic and poorly characterized. The study shows that most subungual bone masses exhibited the pathological features of conventional osteochondromas. Nonetheless, a small number of lesions were pleomorphic and differed from osteochondromas, with abundant fibrous tissue merging irregularly into scattered islets of cartilage that was not organized in columns. Radical excision of the mass achieved complete relief of symptoms and recovery without recurrences in all cases.

Subungual exostosis: case report and review of the literature

Subungual exostosis is typically a benign, acquired tumor of cartilaginous bone occurring on the medial surface of the distal hallux. A 16-year-old boy with subungual exostosis of his left great toe is presented. We evaluated the English language literature on this topic from 1857 to 1994; including our patient, 312 cases have been described. The diagnostic characteristics (histologic and radiologic), etiologic features, and therapeutic management were reviewed. Subungual exostosis more commonly affects women than men in a ratio of 2:1. Most lesions occur in the early twenties; however, a minimum of 51 (16%) of the 312 cases of subungual exostoses appeared in children 18 years of age or younger. Seventy percent of lesions occurred on the first hallux. There was frequently an association with trauma. The diagnosis of subungual exostosis may be suspected from the clinical presentation and confirmed with radiographic examination. The treatment is surgical.

Subungual exostosis

The author describes subungual exostoses as well as their differential diagnoses. Clinical and radiologic features are illustrated. Surgical excision is recommended, following partial toenail avulsion, in the majority of symptomatic cases.

Subungual exostosis in the hand

Although it is thought to be a relatively common tumour, only 34 positively identified cases of subungual exostosis in the hand have been found in the literature to date. 16 further cases are reported, making this the largest published series. Seven cases presented with an incorrect diagnosis. An X-ray easily differentiates the tumour from an osteochondroma of the distal phalanx, a spike of bone from a crush injury, or a response to a penetrating injury called a turret exostosis. Removal of the deformed nail and excision of the mass from the distal phalanx produces a useful finger without pain, tender scar, or resultant nail deformity. No case of malignancy has ever been reported.

Tumors of the nail unit

Tumors of the nail unit are often initially misdiagnosed or diagnosed later in their course than their skin counterparts. This is probably because the nail can obscure the lesion or many nail tumors mimic inflammatory dermatoses of the nail unit. Both benign and malignant tumors of the nail unit are described.

Nail biopsy. Indications and methods

Nail biopsy is a safe and useful diagnostic procedure for many nail disorders when routine clinical and laboratory methods fail to produce a diagnosis. Prerequisites for nail biopsy are an understanding of the surgical anatomy of the nail, adequate anesthesia and hemostasis, and a nail abnormality for which histopathology can provide the diagnosis. Indications and methods for nail biopsy vary according to the site and type of pathology in the nail unit. Nail bed and perionychial biopsies can be performed easily and with minimal scarring. They are most commonly used to diagnose tumors as well as infectious and inflammatory disorders of the nail. The most important reason to biopsy the nail matrix is to make or exclude the diagnosis of melanoma in a patient with longitudinal melanonychia. Great care must be taken in nail matrix biopsy to minimize the risk of permanent nail dystrophy.

Subungual exostosis of the fingers

Subungual exostosis in the digit is an uncommon benign tumor. Only 21 (10%) of 203 cases reported in the literature occurred in the hand. We present a recent case, detailing diagnosis, pathologic findings, and management.

Geriatric nail disorders: diagnosis and treatment

Age-associated nail changes and disorders are common in elderly patients. Characteristic changes in color, contour, growth, surface, thickness, and histology occur in the nail unit as persons become older. Several onychodystrophies are frequently observed in these elderly patients: brittle nails, those induced by faulty biomechanics and trauma, infections, onychauxis, onychoclavus, onychogryphosis, onychophosis, splinter hemorrhages and subungual hematomas, and subungual exostosis. Awareness of the signs and symptoms of the aging nail will enable better assessment and management of the onychologic concerns of this group of older patients.

Nail disease and dermatology

Onychology (the study of nails) is an important area in dermatology. We discuss the dermatologists' opportunity to educate their patients and colleagues about nail disorders, review the diagnostic techniques for evaluating nails, and describe some of the possible topics for additional research.