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 Table of Contents  
CASE REPORT
Year : 2017  |  Volume : 6  |  Issue : 3  |  Page : 187-190

A rare case of subungual exostosis of the hallux in an adolescent: A clinico-pathological review of literature


Department of Orthopaedics, JSS Medical College and Hospital, Mysore, Karnataka, India

Date of Web Publication9-Aug-2017

Correspondence Address:
Supreeth Nekkanti
Department of Orthopaedics, JSS Medical University and Hospital, Agrahara Circle, MG Road, Mysore, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijhas.IJHAS_6_16

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  Abstract 


Osteochondromas and subungual exostosis (SE) are commonly misunderstood conditions. They are widely used synonymously. However, a detailed review of literature tells us that SE is in fact a rare variant of osteochondroma. This peculiar tumor is relatively uncommon; it has not been much remarked in the recent years. We report a case of SE of the hallux in an 18-year-old girl who presented to us with a swelling on her great toe which ulcerated the skin and caused lifting of the nail. We surgically excised the mass and reconstructed the nail and confirmed the diagnosis by histopathological studies. We present this case for its rarity and also because it is often misunderstood and misdiagnosed.

Keywords: Hallux, misdiagnosis, osteochondroma, subungual exostosis


How to cite this article:
Nekkanti S, Siddartha A, Theja S, Sastry P, Gowd A. A rare case of subungual exostosis of the hallux in an adolescent: A clinico-pathological review of literature. Int J Health Allied Sci 2017;6:187-90

How to cite this URL:
Nekkanti S, Siddartha A, Theja S, Sastry P, Gowd A. A rare case of subungual exostosis of the hallux in an adolescent: A clinico-pathological review of literature. Int J Health Allied Sci [serial online] 2017 [cited 2019 Sep 21];6:187-90. Available from: http://www.ijhas.in/text.asp?2017/6/3/187/212597




  Introduction Top


Osteochondromas are small, benign, bone tumor of the foot.[1] They are most often found at the end of small bones, such as phalanx of the toes. On the other hand, subungual exostosis (SE) is an uncommon benign bone tumor arising in the distal phalanx of the digit, beneath, or adjacent to the nail bed. It is considered a rare variant of osteochondroma.[2] The first description of this lesion was by Dupuytren in 1847 when he reviewed his experience with thirty patients suffering from subungual exostoses of the great toe.[1],[3],[4] It has not been much remarked in the recent years. These two entities are often confused to be the same and many a time misdiagnosed. There is very limited literature that explains the difference between these two conditions. The authors in this report attempt to delineate the two tumors.


  Case Report Top


We report a 18-year-old female patient who presented to us with a swelling of the great toe for the past 4 months. It was sudden in onset and gradually progressive. The growth of the swelling led to ulceration of the overlying skin and nail. The mass also caused deformity of the overlying nail.

On clinical examination, a 2 × 2 × 2 oval swelling was observed over the dorsomedial aspect of the tip of the great toe. The swelling had grown through the overlying skin and nail causing a bleeding ulcer over the great toe. The mass was hard and fixed to the bone.

Radiography

X-ray of the foot in anteroposterior and oblique views was done. It revealed a bony growth from the dorsomedial aspect of the distal phalanx of the great toe with a radiolucent cartilaginous cap [Figure 1]. A provisional diagnosis of osteochondroma of the distal phalanx of great toe was made.
Figure 1: Preoperative X-ray

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Histopathology

Epidermis showed neutrophil infiltration [Figure 2]. Circumscribed delineated lesion composed of mature cartilaginous tissue with clustered chondrocytes in a myxoid stroma. Features were suggestive of chondroma. We reached a diagnosis of SE of the distal phalanx of the great toe.
Figure 2: Histopathology image

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Surgery

A curvilinear incision was made over the dorsomedial aspect of skin of the great toe extending over the tip of the great toe. The ulcerated margins were excised. The mass was identified and borders demarcated. The mass was then excised and remnant nibbled out. The consistency of the mass was not hard as expected in an osteochondroma. The mass was sent for histopathological studies. The surgical wound was repaired in layers and healthy nail was sutured back to the nail matrix [Figure 3]. Postoperative X-rays showed that the tumor had been completely excised [Figure 4]. The postoperative period was uneventful and sutures were removed on the 10th postoperative day.
Figure 3: Postoperative clinical photograph

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Figure 4: Postoperative X-ray

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  Discussion Top


SE is a rare bone tumor arising in the distal phalanx of the digit, beneath, or adjacent to the nail bed. It is considered a rare variant of osteochondroma.[2] This peculiar tumor is relatively uncommon; it has not been much remarked in the recent years.[4],[5] This tumor has a predilection to involve the inner border of the distal phalanx of the great toe, but other toes and even fingers may also be affected.[4],[6],[7],[8] Unlike the conventional exostoses, these lesions neither arise adjacent to epiphyseal growth plate which is basal in distal phalanx nor are they found in association with multiple hereditary exostoses.[4]

SE usually develops during adolescence and is more common in females than in males.[5] As was the case, our patient was a female patient in her adolescence, 18-year-old when she presented to us with the complaints.

Clinical examination of these cases reveals typically a solitary lesion, which appears like a small firm lesion, usually located deep to the free edge of the nail. Pain, particularly occurs on walking, due to the friction between the nail plates with the expanding exostosis. The overlying nail is pushed up and is finally detached; leading a mass of fibrous tissue whose surface may become eroded and infected. This mass overlies the exostosis.[5] Our patient presented to us with 4 months history of the mass, which she ignored initially. After 4 months of daily activity, it progressed to the present size and ulcerated the overlying skin and pushing up of the nail.

To explain the differences in presentation, García Carmona et al.[9] proposed a clinical classification scheme based on the clinical signs and symptoms present during examination and the associated disorders of the nail plate, progressing in severity from Type 1 (mild deformity) to Type 4 (medial or lateral condyle). Type 1 deformities are caused by normal or minimal incurvation of the nail plate. Type 2 deformities are a progression of Type 1 in which the exostosis is distal to the nail plate. A Type 3 deformity is associated with exostosis that is under the nail plate. Type 4 deformities are classified as osseous proliferations of either the medial or lateral condyles of the distal phalanx.[9] Using this classification system, our patient's nail would be classified as a Type 2 deformity.

The pathogenesis of SE is not clearly understood in the literature. It has been attributed to be a multifactorial problem. Trauma, chronic infection, tumor, and hereditary abnormality has been commonly described causes in the reviewed literature.[1] Trauma is often described as a precipitating factor, and SE may represent cartilaginous metaplasia occurring in response to acute or chronic irritation.[4] Chronic infection seems to be the result rather than the cause of the underlying lesion.[4] Other studies have postulated that possible etiologies include teratologic abnormalities, form a part of multiple hereditary exostoses, activation of a cartilaginous cyst, or defect in the perichondrial node of Ranvier.[1],[3]

In the initial stages of development, the lesion appears as proliferating fibroblasts in direct continuity with the nail bed where cartilaginous metaplasia can be seen. The cartilage gradually undergoes calcification and ossifies. Later, the areas of enchondral ossification eventually progress to woven bone and then lamellar bone. In the early stage, proliferation of cartilage contributes to the exophytic growth of the lesion while later mature bone dominates the outgrowth.[7] The patient might probably have presented to us in the initial phase of cartilage metaplasia.

Radiographically, an exostosis is seen as a bony outgrowth projects from the dorsal or dorsomedial aspects of the distal portion of a terminal phalanx, and composed of a mature trabeculated bone with attachment to the phalanx; the free end is flat, cupped and smooth, or irregular. Unlike the clinical complaints, the radiological images are modest due to the presence of a large radiolucent cartilaginous cap.[10] There is no cortical disruption or other abnormality of the distal phalanx.[2] Our patient's radiographs were comparable with the literature in the sense of a small bony outgrowth of the distal phalanx surrounded by a large radiolucent cartilaginous cap.

Histologically, the immature lesion only has a thick fibrocartilaginous cap, contributing to exophytic growth of the lesion.[3],[4],[7],[8] The mature lesion comprises a base of trabecular bone with a proliferating fibrocartilaginous cap,[8] thereby differentiating SE from osteochondroma, which has a cartilaginous cap that comprises hyaline cartilage.[8] SE is hypercellular and the cartilage cells may have plump nuclei. However, the lack of anaplasia and its distinct radiographic appearance differentiate SE from chondrosarcoma. Malignant degeneration of SE has not been reported.[3],[4] The histological studies from the sample obtained in our patient showed clusters of cartilaginous cells with minimal osteoid tissue suggesting a diagnosis of SE of the distal phalanx of the great toe.

The clinical presentation leads SE to be easily misdiagnosed, which may result in inadequate or extreme treatments. The histological and radiologic findings make SE distinct. The differential diagnosis of SE includes subungual verruca, granuloma pyogenicum, glomus tumor, carcinoma of the nail bed, melanotic whitlow, keratoacanthoma, subungual epidermoid inclusions and enchondroma, Koenen's tumor, and ingrown toenail.[2] Osteochondroma, enchondromas are cartilaginous tumors arising in the medullar cavity of tubular bones and should not be mistaken for SE.

Surgical excision is the most appropriate treatment; when correctly performed; long-lasting results are obtained.[5] Recurrence rates vary from 11% to 53%;[11] however, if the lesion base is excised at the cortex until the spongy bone is observed, recurrence rates drop to 5%–11%.[8] We have followed up our patient for 18 months, and she is absolutely fine with no evidence of recurrence.

We report this case for its rarity and it being a common cause for misdiagnosis. It is critical for clinicians to identify this condition clinically and to confirm by radiography and histopathological studies. This reduced unwarranted under or over the treatment of this condition and thereby reducing the risk of recurrence. Special care must be taken not to extensively damage the nail matrix while excising this tumor.

SE is a benign fibrocartilaginous lesion of the distal phalanx that is infrequently seen in clinical practice. It should be included in the differential diagnosis of entities presenting with finger/toe tip pathology.

The SE occurs due to repeated trauma in the nail bed which leads to cartilage metaplasia followed by its ossification. Without the nail protection, the nail blade is exposed to the infection, and hence, it must be removed at the earliest. In the absence of the histopathological and radiographical examination, the diagnosis can be mistaken and the treatment inadequate, even crippling. The local excision and the removal of the cartilaginous cap are the elective treatment of the SE.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Tuzuner T, Kavak A, Parlak AH, Ustundag N. Subungual osteochondroma: A diagnostic dilemma. J Am Podiatr Med Assoc 2006;96:154-7.  Back to cited text no. 1
    
2.
Ilyas W, Geskin L, Joseph AK, Seraly MP. Subungual exostosis of the third toe. J Am Acad Dermatol 2001;45 6 Suppl:S200-1.  Back to cited text no. 2
    
3.
Dupuytren G. In: Clark F. Legros (Ed.) On the injuries and diseases of the bones. 20. 4th ed. Publications of the Sydenham Society, London; 1847:408–10.  Back to cited text no. 3
    
4.
Landon GC, Johnson KA, Dahlin DC. Subungual exostoses. J Bone Joint Surg Am 1979;61:256-9.  Back to cited text no. 4
    
5.
Aggarwal K, Gupta S, Jain VK, Mital A, Gupta S. Subungual exostosis. Indian J Dermatol Venereol Leprol 2008;74:173-4.  Back to cited text no. 5
[PUBMED]  [Full text]  
6.
Shaffer LW. Subungual exostoses. Arch Dermatol Syph 1931;24:371-9.  Back to cited text no. 6
    
7.
Dave S, Carounanidy U, Thappa DM, Jayanthi S. Subungual exostosis of the thumb. Dermatol Online J 2004;10:15.  Back to cited text no. 7
    
8.
Dawber RP, Baran R, de Berker D. Disorders of nails. In: Rook/Wilkinson/Ebling Textbook of Dermatology. 6th ed., Vol. 4. Oxford: Blackwell Science; 1998. p. 2815-69.  Back to cited text no. 8
    
9.
García Carmona FJ, Pascual Huerta J, Fernández Morato D. A proposed subungual exostosis clinical classification and treatment plan. J Am Podiatr Med Assoc 2009;99:519-24.  Back to cited text no. 9
    
10.
Carroll RE, Chance JT, Inan Y. Subungual exostosis in the hand. J Hand Surg Br 1992;17:569-74.  Back to cited text no. 10
    
11.
Murphey MD, Choi JJ, Kransdorf MJ, Flemming DJ, Gannon FH. Imaging of osteochondroma: Variants and complications with radiologic-pathologic correlation. Radiographics 2000;20:1407-34.  Back to cited text no. 11
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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