Scaphoid Cysts: Literature Review of Etiology, Treatment, and Prognosis

Abstract

Background: Cystic lesions of the carpal bones are rare entities that are infrequently reported in the literature. Scaphoid intraosseous cystic lesions represent a rare subset of carpal bone cysts. This review aims to summarize the available evidence on the evaluation and treatment of scaphoid cystic lesions to help guide clinical management. Methods: Systematic electronic searches were performed using PubMed, Ovid, and Embase databases. Studies included were graded for their risk of bias. Pooled descriptive statistics were performed on incidence, etiology, physical exam findings, treatment, and follow-up. Results: A total of 38 patients representing 41 scaphoid cystic lesions were pooled from 27 articles. Patients presented with wrist pain without fracture (n = 27), pathological fracture (n = 9), swelling only (n = 1), or were asymptomatic (n = 4). Cystic lesions of the scaphoid were initially revealed on imaging with radiographs alone (n = 22), radiographs in combination with computed tomography (CT) (n = 10) or magnetic resonance imaging (n = 6), CT alone (n = 1), or using all 3 modalities (n = 2). Intraosseous ganglia were identified most frequently (n = 31), followed by “bone cyst-like pathological change” (n = 3), unicameral bone cysts (n = 2), aneurysmal bone cysts (n = 2), primary hydatid cysts (n = 2), and cystic like changes post fall (n = 1). Treatment modalities included curettage and bone graft (n = 39) or below-elbow cast (n = 2). On follow-up (average of 21.3 months; n = 40), all patients improved clinically after treatment and were found to have full wrist range of motion without pain (n = 31), slightly reduced grip strength (n = 3), limited range of motion (n = 2), or persistent mild discomfort (n = 2). Conclusions: Scaphoid cystic lesions are most commonly intraosseous ganglia, but can include other etiologies as well. The main presenting symptom is radial wrist pain that usually resolves after treatment. The presence of intracarpal cystic lesions should be considered in the differential diagnosis of wrist pain.

Introduction

Cystic lesions of the carpal bones are rare entities that have not been frequently reported in the literature to date.³⁵ A cyst is defined as a closed sac, having a membrane that separates it from the surrounding tissue. Most often, they are found on routine imaging and are otherwise asymptomatic.¹³ However, a certain subgroup of cysts can present with focal findings on physical examination,³⁵ such as nonspecific wrist pain, tenderness to palpation and edema. Risk factors for the formation of such cysts are older age and chronic vibration transmitted through machinery.³⁵

Scaphoid specific intraosseous cystic lesions represent an uncommon subset of carpal bone lesions. The incidence and management of cystic lesions of the scaphoid bone are neither well understood nor frequently reported. Thus far, different types of cystic lesions have been described in numerous case reports and series, best studied and defined as intraosseous ganglion cysts, or degenerative cysts secondary to osteoarthritis.⁵

Currently, there is no consolidated description of scaphoid cystic lesions that facilitates appropriate diagnosis, management, and follow-up. The aim of the present study is to elucidate the etiology, incidence, presenting symptoms, diagnostic tools, treatment, and complications of scaphoid cystic lesions through a systematic review of the literature. Herein, the authors summarize these findings and provide the reader with an evidence-based clinical approach to management.

Methods

The protocol for this systematic review is registered in the National Institute for Health Research’s database: PROSPERO. http://www.crd.york.ac.uk/PROSPERO/ (Registration number: CRD42017060798)

Data Sources and Search Strategy

A search of the National Library of Medicine (PubMed), Embase biomedical, and OVID databases was carried out using a search strategy that included literature published between the years 1984 and 2016. The search was limited to publications in peer-reviewed journals, involving human subjects, and written in the English language. The following search terms were used: “scaphoid,” “carpal bones,” “carpal navicular,” and “wrist bones.” These terms were then combined with “cyst” and “cystic.” Design and execution of this review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist.²¹

Study Selection and Data Extraction

Two reviewers independently screened results of the search using a 2-step process. In the first step, studies that described a cystic lesion of the scaphoid in the title or abstract, based on strict inclusion and exclusion criteria, were retained. The inclusion criteria consisted of radiologic evidence of a cystic lesion in the scaphoid or confirmation of a cystic structure on pathology. Exclusion criteria included scaphoid lesions that did not extend into the intraosseous structure or cystic lesions in other carpal bones. The authors also eliminated cases with concomitant Keinböck disease (avascular necrosis of the lunate), as the latter would likely bear a greater impact on the approach to management and resultant prognosis than a scaphoid cyst alone.²² Degenerative osteoarthritic cystic lesions were also excluded given their high prevalence and benign course. In the second stage of the screening process, the full text was evaluated to distinguish those studies that specifically reported on cysts originating from or localized to the scaphoid bone. Due to the paucity of existing literature, case series and case reports were included in the search. From the reports selected, the data extracted included authors, year of publication, study design, number of patients, patients age and sex, physical exam findings, diagnostic modalities, cyst characteristics, treatment strategies, prognosis, and complications.

Quality Assessment

The articles were assigned a quality score for evidence presented and risk of bias using the American Society of Plastic Surgery (ASPS) critical appraisal check sheet.⁴ Each article included for analysis was also designated an appropriate level of evidence, using a rubric that defines level of evidence in plastic and reconstructive surgery.

Results

The preliminary search extracted 2323 citations, of which 147 articles were included based on the filter strategy previously described. Following appraisal of the articles’ (n = 147) full text, the second screen identified 27 articles, published between 1984 and 2016, reporting on a total of 38 patients that met the inclusion criteria (Figure 1).^{1,3,6-16,17-20,25,26,28-30,33,34,36-38} Among the 38 patients (14 male, 24 female), 3 had bilateral cystic lesions, for a total of 41 scaphoid cystic lesions. The findings from each study are summarized in Table 1. The mean age of all patients was 34.2 years (n = 38; range: 14-60).

Figure 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram representing results from PubMed, Embase, and Ovid databases.

Table 1.

Summary of Findings on Scaphoid Cysts.

Authors	Year	Study type	Age	Sex	Hand	Clinical manifestations	Diagnosed by	Surgical pathology	Cyst type & location	Treatment	Follow-up	Prognosis/complications
Abouchane, M.	2015	Case report	29	M	R+L	Pain (bilateral) Pathological fracture (L only)	Plain radiography	Yes	Intraosseous ganglion, waist bilaterally	Curettage and autologous distal radius bone graft. Left wrist internal fixation with K-wires and immobilized in cast for 1.5 months	18	Good functional outcomes with return to work and normal activities
Albaladejo, F. M.	1993	Case report	56	F	L	Pain	Plain radiography, CT	Yes	Intraosseous ganglion, waist	Curettage and autologous bone graft from radius	8	Bony consolidation on radiograph
Buldu, H.a	2009	Case report	23	F	L	Pain	Plain radiography, MRI	Yes	Intraosseous ganglion	Curettage and autologous distal radius bone graft	36	No pain
			23	F	L	Pain	Plain radiography, MRI	Yes	Intraosseous ganglion	Curettage and autologous distal radius bone graft	36	No pain
Bulut, M.	2012	Case report	31	F	L	Pain after fall	Plain radiography, MRI	Yes	Primary hydatid cyst, proximal pole	Curettage, irrigation with hypertonic saline and povidone-iodine solution, followed by bone allograft. Thumb spica cast for 3 weeks	7	No pain or swelling. Full ROM. Normal clinical exam, negative serological tests, no radiological evidence of recurrence
Castellanos, J.	2001	Case report	33	M	L	Pathological fracture, pain	Plain radiography, CT	—	Intraosseous ganglion, proximal pole	Below-elbow cast for 8 weeks	7.125	Spontaneous cyst regression and healing of fracture on CT. Full ROM, symmetrical grip strength, no recurrence. Discomfort only with intense effort
Chantelot, C.	1998	Case report	22	M	L	Pathological fracture, pain	Plain radiography, CT	Yes	Intraosseous ganglion, waist	Curettage, autologous iliac bone graft, and pin fixation. Immobilized in cast for 2 months	6	No pain, full ROM, no recurrence. Slightly reduced strength compared with contralateral side
Chen, F. and J. A. Shapiro	1999	Case report	44	F	R	Pain, difficulty grasping objects	Plain radiography, MRI, bone scan	Yes	Intraosseous ganglion, distal pole	Curettage, autologous bone graft from radius, and pin fixation. Unsuccessful immobilization preoperatively	5	Complete symptom resolution after excision No radiological evidence of recurrence
De Smet, L. and G. Fabry	1994	Case report	30	M	R	Pathological fracture, pain	Plain radiography	—	Intraosseous ganglion, waist	Below-elbow cast for 2 months	6.5	Full ROM, bony consolidation on radiograph. Mild discomfort
Fealy, M. J.	1995	Case report	49	F	R	Pain and swelling	Plain radiography, MRI	Yes	Intraosseous ganglion, waist	Curettage and radial styloid bone graft	0.75	Graft retention within cystic space
Ikeda, M. and Y. Oka	2000	Case series	32	F	R	Pain and swelling	Plain radiography	Yes	Intraosseous ganglion, distal pole	Curettage and iliac bone graft	29.3	Bony consolidation. Return to normal activities, without disability. No pain, no recurrence
			23	M	L	Pain and swelling	Plain radiography	Yes	Cyst-like lesion	Curettage and iliac bone graft	29.3	Bony consolidation. Return to normal activities, without disability. No pain, no recurrence
			47	F	L	Pain, swelling, and fracture	Plain radiography	Yes	Cyst-like lesion, entire bone	Curettage and iliac bone graft	29.3	Bony consolidation. Return to normal activities, without disability. No pain, no recurrence
			21	M	R	Pain and swelling	Plain radiography	Yes	Cyst-like lesion	Curettage and iliac bone graft	29.3	Bony consolidation. Return to normal activities, without disability. No pain, no recurrence
Jain, S.	2011	Case report	40	F	R	Pain	Plain radiography, CT	Yes	Intraosseous ganglion, waist	Curettage and iliac bone graft. Immobilized in cast for 3 weeks	12.8	Full ROM, return to work No radiological evidence of recurrence, normal grip strength, significant improvement in pain
Javdan, M.	2012	Case report	48	M	L	Acute pain	Plain radiography	Yes	Unicameral bone cysts, distal pole	Prophylactic antibiotics, curettage, thumb spica cast for 3 weeks, followed by distal radius bone graft	12	No pain and full ROM after cyst excision. Good functional outcomes
			30	F	R	Acute pain	Plain radiography	Yes	Unicameral bone cysts, distal pole	Curettage, thumb spica cast for 3 weeks, followed by distal radius bone graft	12	No pain and full ROM after cyst excision. Good functional outcomes
Kligman, M	1997	Case report	44	F	R+L	Pain (bilateral)	Plain radiography, CT + Bone scan (right only)	Yes	Intraosseous ganglion, multicystic in waist and proximal pole bilaterally	Curettage, distal radius bone graft, followed by palmar splint for 4 weeks	12	No pain, full ROM
Lao, L. F.	2014	Case report	39	F	L	Pain	Plain radiography	Yes	Intraosseous ganglion, waist	Curettage under brachial plexus block. Cystic space cauterized with carbol, neutralized with alcohol, and irrigated with NS. Cavity filled with radial bone graft	8	Symptom resolution postoperatively. No clinical or radiological evidence of recurrence
Lebus, G. F.	2016	Case report	14	F	L	Pathological fracture, pain	Plain radiography, CT, MRI, biopsy	Yes	Aneurysmal bone cyst, entire distal two-thirds	Curettage, phenol adjuvant therapy, local autologous bone grafting with supplemental allograft. Prolonged immobilization (duration not specified)	23	Prolonged postoperative healing. Clinically asymptomatic and no radiological evidence of recurrence
Logan, S. E.	1992	Case report	14	F	R+L	Pain (bilateral)	Plain radiography	Yesb	Intraosseous ganglion, waist bilaterally	Curettage and distal radius bone graft. Left wrist casted for 6 weeks	20.5	Symptom resolution postoperatively. Asymptomatic at 17-month and 24-month follow-up for right and left scaphoid, respectively
Mnif, H.	2010	Case report	30	F	L	Pain	Plain radiography, CT	Yes	Intraosseous ganglion, proximal portion	Curettage and distal radius bone graft. Immobilization in a splint for 3 weeks	48	Asymptomatic with normal ROM, no radiological evidence of recurrence
Peterson, T.c	1993	Case report	21	M	—	Pain	Plain radiography	—	Intraosseous ganglion	Curettage and bone graft	—	—
Ramboaniaina, S.	2009	Case report	16	F	L	Pain	Plain radiography, CT	Yes	Aneurysmal bone cyst, distal pole	Curettage under general anesthesia and iliac bone graft. Immobilized in cast for 6 weeks	12	Asymptomatic and normal ROM, no recurrence
Sbai, M.A.	2016	Case report	21	M	R	Pain, pathological fracture	Plain radiography, CT	Yes	Intraosseous ganglion, proximal pole	Curettage and distal radius bone graft. Immobilized in cast for 5 weeks	13.5	No pain, full grip strength, slightly limited ROM. No radiological evidence of recurrence
Sakamoto, A.	2013	RCR	42	M	L	Pathological fracture	Plain radiography	Yes	Intraosseous ganglion, distal pole	Curettage and autologous bone graft	24	Bony consolidation. No recurrence
			54	F	R	Pain	Plain radiography	Yes	Intraosseous ganglion, distal pole	Curettage and autologous bone graft	24	Bony consolidation. No recurrence
Salunke, A. A.	2016	Case report	30	M	R	Pain	Plain radiography, CT, MRI	Yes	Intraosseous ganglion, proximal pole	Curettage, autologous iliac bone graft, and K-wire fixation. Immobilization in thumb spica cast for 6 weeks	3	Good functional outcomes with return to work and activities of daily living. No evidence of recurrence
Serbest, S.	2016	Case report	22	F	L	Pain	Plain radiography, MRI	Yes	Primary hydatid cyst, proximal pole	Curettage and irrigation with hypertonic solution and povidone-iodine solution. Cavity filled with bone allograft. Short arm splint with thumb support for 2 months	7	No pain or swelling. No recurrence
Shimizu, K.	1984	Case report	52	F	L	Pain	Plain radiography, CT	Yes	Intraosseous ganglion, waist	Curettage and iliac bone graft	9	No radiological evidence of recurrence, mildly reduced grip strength compared with contralateral hand
Uriburu, I. J. and V. D. Levy	1999	Case series	60	F	L	Swelling	Plain radiography	Yes	Intraosseous ganglion, waist	Curettage under brachial plexus block, irrigation with normal saline followed by bone graft	47	Normal wrist ROM and grip strength, no recurrence
			45	F	R	Asymptomatic	Incidentally on Plain radiography	Yes	Intraosseous ganglion, proximal pole	Curettage under brachial plexus block, irrigation with saline, and bone grafts	47	Normal wrist ROM and grip strength, no recurrence
			59	F	R	Asymptomatic	Incidentally on Plain radiography	Yes	Intraosseous ganglion, distal two-thirds	Curettage under brachial plexus block, irrigation with saline, and bone grafts	47	Normal wrist ROM and grip strength, no recurrence
			46	F	L	Pain	Plain radiography	Yes	Intraosseous ganglion, waist	Curettage under brachial plexus block, irrigation with saline, and bone grafts	47	Normal wrist ROM and grip strength, no recurrence
			44	M	L	Asymptomatic	Incidentally on Plain radiography	Yes	Intraosseous ganglion, distal pole	Curettage under brachial plexus block, irrigation with saline, and bone grafts	47	Normal wrist ROM and grip strength, no recurrence
			30	F	L	Asymptomatic	Incidentally on Plain radiography	Yes	Intraosseous ganglion, waist	Curettage under brachial plexus block, irrigation with saline, and bone grafts	47	Normal wrist ROM and grip strength, no recurrence
Walaszek, I. and A. Zylukd	2007	Case report	14	M	—	Pain	CT	Yes	Foreign body cyst	Curettage and allogenic bone graft	6	Complete recovery
Yakoubi, M.	2009	Case report	21	M	L	Pathological fracture, pain	Plain radiography	Yes	Intraosseous ganglion, waist	Curettage under brachial plexus block, vascularized distal radius bone graft with pin fixation. Immobilized in cast for 45 days	12	Normal ROM, 90% grip strength compared with contralateral hand; no recurrence

Note. CT = computed tomography; MRI = magnetic resonance imaging; ROM = range of motion; NS = normal saline; RCR = retrospective chart review.

^aCase report in identical twin sisters.

^bRight wrist only as no cyst was found in the left wrist at the time of operation, likely due to rupture.

^cData extracted from reviews.

^dData extracted from abstract.

Clinical Presentation

Scaphoid cystic lesions initially presented as acute or chronic wrist pain without fracture (n = 27), with pathological fracture (n = 9), swelling (n = 1), or were asymptomatic at initial visit (n = 4) (Table 2). Among those presenting with wrist pain without evidence of fracture (n = 27), only 5 cases were attributed to a preceding trauma. Of the 9 associated with pathological fracture, 6 patients reported an inciting trauma, 2 denied history of trauma, and in the remaining case, history of trauma was not elucidated.

Table 2.

Distribution of Scaphoid Cysts According to Sex and Clinical Presentation.

Type of cyst	N (%)	Sex		Mean age	Clinical manifestation
					Pain without fracture (…± swelling)	Pathological fracture	Asymptomatic	Swelling only
	Total N = 41	M	F
Intraosseous ganglion	31 (73.8)	10	18	36.9	19	7	4	1
Cyst-like lesion	3 (7.1)	2	1	30.3	2	1	0	0
Unicameral bone cyst	2 (4.8)	1	1	39	2	0	0	0
Aneurysmal bone cyst	2 (4.8)	0	2	15	1	1	0	0
Primary hydatid cyst	2 (4.8)	0	2	26.5	2	0	0	0
Foreign body cyst	1 (2.3)	1	0	14	1	0	0	0

Evaluation and Further Investigations

Cystic lesions of the scaphoid were initially revealed on imaging with radiographs alone (n = 22), radiographs in combination with either computed tomography (CT) (n = 10), magnetic resonance imaging (n = 6), or both (n = 2). In 1 patient, CT alone demonstrated a cystic lesion of the scaphoid. The location of 35 cysts were recorded, and was most common within the scaphoid waist (n = 15), followed by the distal pole (n = 10), the proximal pole (n = 7), and in the entire scaphoid (n = 1). One patient had multiple cystic lesions in the scaphoid waist and proximal pole bilaterally (n = 2).

For scaphoid lesions identified as intraosseous ganglia (IOG) (n = 31), location included the scaphoid waist (n = 15), distal pole (n = 5), proximal pole (n = 5), and distal two-thirds of the scaphoid bone (n = 1). Two patients had multiple IOG, localized to the scaphoid waist and proximal pole. In a few cases (n = 3), the location of the IOG was not specified. Among the scaphoid lesions designated as bone cyst-like pathological changes (n = 3), 1 patient presented with multiple cystic lesions throughout the scaphoid, while for the other 2 cases, imaging findings were not provided nor described. Both primary hydatid cysts were found in the proximal pole (n = 2). In all cases of aneurysmal bone cysts (n = 2) and unicameral bone cysts (n = 2), lesions were located in the distal pole. One patient developed a cystic lesion secondary to a foreign body; however, location was not specified.

Pathological Diagnosis

Pathologic analysis confirmed the diagnosis in all surgically excised scaphoid lesions (n = 37). In 2 patients, scaphoid lesions were treated conservatively and in another, rupture precluded definitive treatment and analysis. Surgical pathology for the remaining lesion was not retrieved.²⁵ Intraosseous ganglia (IOG) were most commonly identified (n = 31), followed by bone cyst-like pathological change (n = 3), primary hydatid cysts (n = 2), aneurysmal bone (n = 2), and unicameral bone cysts (n = 2). There was 1 case of a scaphoid cyst in a 14-year-old boy that formed around a foreign body introduced secondary to a fall.²³ Among the cases in which dimensions were provided, IOG (n = 17) and unicameral bone cysts (n = 2) measured an average of 8.8 × 8.2 mm and 6.0 × 4.5 mm, respectively.

Management

Ninety-five percent (n = 39) of scaphoid lesions were successfully treated surgically with curettage and bone graft. Internal fixation with Kirschner wires was additionally performed in 5 of these cases, of which 3 had an associated pathological fracture. Postoperatively, 14 patients were casted for a mean of 5 weeks (range: 3-8 weeks). In the 2 patients managed conservatively with casting for 8 weeks, spontaneous cystic regression without recurrence was observed. Of note, the latter 2 patients who initially presented with pathological fractures ultimately demonstrated radiographic evidence of healing. However, in 1 patient, mild wrist discomfort was noted at 9-month follow-up and discomfort with intense effort was described in the other patient at 1 year.

Follow-up

None of the studies reported recurrence during a mean follow-up of 21.3 months (n = 40), with only 1 patient lacking follow-up. However, 18.4% (n = 7) of patients remained symptomatic despite excision. Symptoms included reduced grip strength compared with the contralateral side (n = 3), limited range of motion (n = 2), or persistent wrist discomfort (n = 2). The 2 patients reporting discomfort, after 9- and 12-month follow-up, respectively, were treated for a pathological fracture with a below-elbow cast only for 2 months.^8,11 Notably, 5 of the 7 patients with poor outcomes after treatment had radiographic evidence of a pathological fracture at the time of diagnosis.^8,9,11,30,38

Discussion

This review was successful in identifying multiple cases of cystic lesions of the scaphoid, delineating etiology, clinical presentation, radiologic findings, and treatment options. This review demonstrated that patients with cystic lesions of the scaphoid present primarily with wrist pain or pathological fracture. It is important to note that although a patient may not recall experiencing an acute trauma, microtraumas and repetitive motion could lead to wear and tear of the joint capsule thereby predisposing formation of the cystic lesion.² Although intraosseous cystic lesions may be rare, the hand specialist should consider the possibility in a patient with pertinent exam findings and no other diagnosis. The differential diagnosis of painful radiolucent lesions of all carpal bones includes fibrous dysplasia of bone, bone cysts, osteoid osteoma, osteoblastoma, chondroblastoma, osteosarcoma, benign cystic lesions, and osteomyelitis.⁷

In this study, IOG were the most common type of cystic lesion found in the scaphoid (n = 31), most frequently in the waist of the bone (n = 16). The majority of patients presented with pain (n = 25) with or without a pathological fracture (n = 7). In general, ganglia account for 60% of benign tumors of the hand and wrist.²⁰ The incidence is 3-fold higher in women than in men, which was also confirmed in this review.²⁰ The most commonly reported location of IOG is in the lower limbs around the ankle joint and the femoral head.^20,28Among the bones of the hand and wrist, the scaphoid and lunate are the most commonly affected.³¹ Although the exact etiology of IOG remains unclear, the leading hypothesis is myxomatous degeneration of connective tissue precipitating cyst formation.³⁶ On imaging, IOG appear as well-defined unilocular or multilocular radiolucent lesions with marginal sclerosis. Disruption of the cortex may or may not be present. Macroscopically, they are described as yellowish-gray with a gelatinous consistency. Histopathology confirms the diagnosis, with characteristic findings of mucin-rich fluid surrounded by a layer of thick fibrous connective tissue with no true epithelial or synovial lining.^14,29,36

A hydatid cyst was seen in 2 patients in this review (2 females, aged 22 and 31 years), both located in the proximal pole of the scaphoid (n = 2) and both patients presenting with wrist pain. On gross examination, they contained clear fluid surrounded by a white germinative membrane. They have been described to occur secondary to parasitosis caused by Echinococcus granulosus.⁷ Hydatid cysts are rare with an incidence ranging between 3 and 50 per 100 000.34 The great majority of hydatid cysts (90%) form in the liver, spleen, and lung, whereas bone involvement is seen in only 0.5% to 4%.³⁹ A standard treatment protocol for osseous hydatid cysts has yet to be described owing to the limited number of cases. An accepted approach to treatment is surgical excision followed by irrigation of the cystic cavity with a scolicidal agent such as 5% silver nitrate, hypertonic saline, or povidone-iodine solution.³⁹ The main difference with other cysts is that the patient should be started on a course of antihelminthic therapy for approximately 3 months.³³

Aneurysmal bone cyst, seen in 2 patients (2 females, ages 14 and 16 years), is defined as a benign cystic lesion of bone composed of blood-filled spaces separated by connective tissue septa containing fibroblasts, osteoclast-type giant cells, and reactive woven bone.²⁶ In this review, both patients presented with the cystic lesion in the distal pole of the scaphoid and with wrist pain as their primary complaint (n = 2).

Unicameral bone cyst (or simple bone cyst) was also seen in 2 patients (1 male aged 48, and 1 female aged 30 years). It represents a benign expansile lesion of unclear etiology that commonly affect the long bones (50%-60% proximal humerus; 30% proximal femur) of male children aged 5 to 15 years.¹⁵ Most cases are asymptomatic and found incidentally, or become symptomatic following pathological fracture.¹⁵ In contrast, the 2 cases of unicameral bone cysts of the scaphoid included in this review were diagnosed on radiographs in symptomatic adult patients presenting with acute wrist pain. In both patients, the cystic lesion was localized to the proximal pole of the scaphoid (n = 2). Grossly, they were lined by a thin layer of fibrous tissue and contained spicules of reactive bone.¹⁵

Scaphoid cystic lesions are most often identified on plain radiographs, which are also sufficient for monitoring cyst progression and recurrence after treatment.²⁴ The main presenting symptom of scaphoid cysts is wrist pain. Once symptomatology arises, conservative treatment modalities can be initiated, including anti-inflammatory medications, immobilization, and lifestyle modifications to reduce the load applied to the affected hand.¹⁵ Ultimately, surgical treatment is indicated for cystic lesions causing persisting pain refractory to conservative management and for those associated with a pathological fracture or signs of cortical erosion.²³ The goal of surgical intervention is complete removal of the scaphoid lesion, to ensure that no cystic remnants remain. Interestingly, this review identified 2 cases of symptomatic IOG that spontaneously regressed with healing of a pathological fracture following immobilization alone.^16,18 The literature reports on only 4 cases of asymptomatic scaphoid cysts, specifically IOG, that were found incidentally on plain radiographs obtained for other reasons. Treatment with curettage and bone grafting was indicated in all 4 of these cases as the cysts were progressively replacing the cancellous substance of the scaphoid bone.³⁶ Observation for truly asymptomatic cysts is reasonable, especially in the elderly population in which the most likely diagnosis is a degenerative cyst. Degenerative cysts should be considered in the context of long-standing osteoarthritis in association with other degenerative changes such as subchondral sclerosis, osteophytes, and joint space narrowing.³²

Traditional management of cystic lesions in the wrist and hand is curettage with bone grafting, which was the only surgical treatment implemented in the studies reviewed. Other modalities include intracystic injection of methylprednisolone acetate, structural support with flexible intramedullary nailing, decompression with multiple drill holes, cannulated screws, or any combination of the above. In comparison with simple curettage, an arthroscopically assisted minimally invasive technique of debridement and grafting of IOG under fluoroscopic guidance has been described.⁵ When compared with curettage, significant and enduring improvement in pain scores and functional activity was observed, without the morbidity associated with open procedures.⁵ The use of a vascularized bone graft may also be particularly beneficial in treating cystic lesions with an associated pathological fracture.^13,30 Finally, postoperative immobilization of the wrist is essential, as noted in this review for a mean of 5 weeks, to allow for complete resolution of symptoms.

Limitations

There are several limitations that have been identified with this review. In view of the paucity of reported cases of cystic lesions of the scaphoid bone, the level of evidence of the studies included is considerably low. Three articles (case series) were classified as level IV evidence, with the remainder (n = 25) classified as level V evidence case reports. Large retrospective or prospective datasets would be valuable in elucidating a more evidence-based management of scaphoid cysts, especially in terms of differentiating the effectiveness of divergent treatment strategies. Given that the large majority of the patients included in this review were symptomatic upon presentation, it remains possible that they were experiencing more advanced and destructive cysts, and thus correspondingly, management favored a more aggressive surgical approach. Finally, the studies failed to disclose any donor site complications among those patients who underwent bone grafting, which can cause significant morbidity.¹⁴