Subungual Giant Cell Tumor of the Tendon Sheath: An Unusual Location

J Clin Aesthet Dermatol. 2024;17(12):25–27.

by Neena Edupuganti, BA, and Joseph M. Dyer, DO

Ms. Edupuganti and Dr. Dyer are with the Philadelphia College of Osteopathic Medicine, Georgia Campus in Suwanee, Georgia.

ABSTRACT: Giant cell tumors of tendon sheath (GCTTS), also known as synovialomas, are benign tumors that originate from the fibrous sheath, or soft tissue, that surround tendons. These tumors predominantly present on the hand, but can present in the wrist, ankle, knee, elbow, or hip. The classic presentation of GCTTS is a painless, firm, slow growing mass present for weeks to months. The pathogenesis of GCTTS remains unknown. Histopathological examination of the tumor is required to confirm the diagnosis. The preferred treatment is surgical excision with long-term follow up. To our knowledge, this is the third reported case of GCTTS originating in the subunguium and the first reported case of GCTTS in the subunguium of the toe.

Keywords: Giant cell tumor of tendon sheath, synovialoma, toenail, nail, hyponychium, subungual neoplasm

Introduction

Giant cell tumors of tendon sheath (GCTTS), also known as synovialomas, are benign tumors that originate from the fibrous sheath, or soft tissue, that surround tendons.¹ These tumors predominantly present on the hand, commonly near interphalangeal joints of the digits.² The classic presentation of GCTTS is a painless, firm, slow growing mass present for weeks to months. The preferred treatment is surgical excision with long-term follow up.^1,3

Here, we present an unusual case of GCTTS in the subungual region of the distal phalanx of the toe in an adolescent male. To our knowledge, this case report is the first in the literature to describe GCTTS presenting in the subungual location on the toe. 

Case report. A 16-year-old male patient presented with a protruding lesion under the nail of the right fourth toe which had been present for four months. The patient denied any pain, itching, or bleeding. The patient reported playing soccer and had a history of acne and eczema. Otherwise, the patient had no remarkable past medical, surgical, or social history and had no known allergies. There was no previous personal or family history of skin cancer or melanoma. Daily medications included topical clindamycin phosphate 1% and diphenhydramine 25mg tablet as needed.

On physical examination, the lesion presented as a 0.7 x 0.5 x 0.3cm firm, desiccated, dark subungual papular projection located on the right distal phalanx of the fourth toe (Figure 1). The lesion was nontender.

After administration of local anesthesia, an excisional biopsy was performed. On removal, the lesion appeared keratinaceous and somewhat similar in consistency to a nail plate (Figures 2 and 3). Histopathology revealed a dermal nodule composed of spindle-shaped fibroblasts, siderophages, and giant cells in a dense fibrous stroma (Figure 4). Immunohistochemical staining was positive for CD-68 and Factor 13a antibodies and negative for Melan-A. A diagnosis of giant cell tumor of tendon sheath was rendered. Three weeks following excision, the treatment site was healing appropriately without tenderness and with good capillary refill in the toe. 

Three months after excision of the lesion, the patient visited a podiatrist who performed a plain film and magnetic resonance imaging of the right foot, showing no bone erosions, soft tissue pathology, or extraosseous lesions of the right fourth phalanges. No additional treatment was performed.

Seventeen months later after excision of the neoplasm, the hyponychium of the right fourth toe was clear, apart from mild scaling. There was good capillary refill in the toe, and the patient denied any symptoms or limitations with motion of the joint. 

Discussion

GCTTS are defined as benign, firm soft tissue tumors that gradually enlarge in size over weeks to years.¹ These tumors most commonly occur on the hand, but can present in the wrist, ankle, knee, elbow, or hip.² The tumor is usually painless, however, depending on the size of the mass and involvement with adjacent structures, occasional numbness or tingling may be present and joint or tendon function may be affected.²

The pathogenesis of GCTTS remains unknown, but some authors suggest it might be related to trauma, inflammatory responses, lipid metabolism, hyperplastic changes, chromosomal abnormalities, and other factors.^4–6

Histopathological examination of the tumor is required to confirm the diagnosis.⁷ Histopathologically, GCTTS is composed of a variety of cells, including monocytes, multinucleated giant cells, fibroblasts, and foam cells.⁷ Other imaging modalities, such as ultrasound, x-ray, magnetic resonance imaging should be used in conjunction to evaluate for soft tissue masses, bony erosions, extra-articular manifestations, vascularity, cystic structures, the tumors relationship with surrounding structures, and other characteristic features of the tumor.^2,6,7

GCTSS have a high recurrence rate of up to 44 percent following excision and can invade local structures which can impair the mechanical function of the involved tendon or joint.^1,2,5–7 To minimize the risk of recurrence and spread of the tumor after diagnosis, the treatment for GCTTS is complete surgical removal of the tumor and long term follow up.^1,2,3,5

Here, we present an unusual case of a GCTTS in the subungual region of the distal phalanx of the toe. Presentation of GCTTS in a male pediatric patient is less typical, as GCTTS commonly affects females in their third to fifth decade of life. In an article that reviewed 20 cases of GCTTS presentations on the foot and ankle, none of them were subungual, confirming our case is very rare.⁸ Despite the rarity of this case, clinicians should be aware of isolated presentations of this tumor and have a low threshold for biopsy when considering GCTTS. Definitive diagnosis and early excision of the neoplasm is particularly important due to the high rate of recurrence and risk of invasion of adjacent structures. To our knowledge, this is the third reported case of GCTTS originating in the subunguium and the first reported case of GCTTS in the subunguium of the toe.^9,20

References 

1. Xie M, Xiao K, Fang ZH, et al. Giant cell tumor of the tendon sheath of the toe. Orthop Surg. 2011;3(3):211–215. 
2. Shukla M, Arora R. Giant cell tumor of the tendon sheath in a male pediatric patient. J Pediatr Health Care. 2021;35(4):430–434. 
3. Fitzpatrick JE, Morelli JG. Dermatology Secrets Plus. 4th ed. Elsevier/Mosby; 2011.
4. Kondo RN, Pavezzi PD, Crespigio J, et al. Giant cell tumors of the tendon sheath in the left hallux. An Bras Dermatol. 2016;91(5):704. 
5. Lv Z, Liu J. Giant cell tumor of tendon sheath at the hand: a case report and literature review. Ann Med Surg (Lond). 2020;58:143–146. 
6. Huang CG, Li MZ, Wang SH, et al. Giant cell tumor of tendon sheath: a report of 216 cases. J Cutan Pathol. 2023;50(4):338–342. 
7. Boeisa AN, Al Khalaf AA. Giant cell tumor of tendon sheath of the distal phalanx. Cureus. 2022;14(9):e29461. 
8. Zhang Y, Huang J, Ma X, et al. Giant cell tumor of the tendon sheath in the foot and ankle: case series and review of the literature. J Foot Ankle Surg. 2013;52(1):24–27. 
9. Abimelec P, Cambiaghi S, Thioly D, et al. Subungual giant cell tumor of the tendon sheath. Cutis. 1996;58(4):273–275.
10. Richert B, Andr J. Laterosubungual giant cell tumor of the tendon sheath: an unusual location. J Am Acad Dermatol. 1999;41(2 Pt 2):347–348.