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Calcifying Aponeurotic Fibroma of theHand: Radiologic Differentiation from

Giant Cell Tumors of the Tendon SheathWendy L. Parker, MD, PhD, Robert R. Beckenbaugh, MD,

Kimberly K. Amrami, MD

From the Departments of Orthopedic Surgery and Radiology, Mayo Clinic, Rochester, MN.

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n 11-year-old, healthy, right-hand–dominantboy presented with a 2-year history of aslow-growing mass in the palm of the left

and. There was a vague history of possibly a remoteplinter in the area but no other reported trauma. Theass was painless apart from mild discomfort with

irect pressure noted while gripping. The patientenied any local neurologic symptoms and was oth-rwise systemically well without fevers or other con-titutional features.

Physical examination showed a nontender, firmass measuring 2 � 2 cm overlying the volar aspect

f the fifth metacarpal head in the palm (Fig. 1). Theverlying skin was unremarkable, nonadherent, andithout identifiable punctures sites or dimpling.ransillumination showed a slightly less translucentrea compared with the surrounding tissue and theresence of a prominent vessel along the ulnar aspectf the mass. Two-point discrimination was 4 mmhroughout the hand. Normal strength and motionere noted without evidence of joint contracture.he mass appeared fairly well encapsulated and didot move with the overlying flexor tendons; how-ver, it was fixed firmly to the underlying soft tissues.

Radiographs were obtained in the anteroposteriornd lateral positions (Fig. 2). A soft-tissue mass wasdentified along the palmar and radial aspects of theeft small finger proximal phalanx extending from theroximal diaphysis to the metacarpophalangeal jointegion. The adjacent bone cortex was intact. Multipleunctate densities were visible within the mass sug-estive of a chondroid matrix.A high-resolution magnetic resonance image

MRI) of the hand was obtained with and withoutadolinium. The examination showed a heteroge-eously enhancing soft-tissue mass at the ventralase of the fifth metacarpophalangeal joint abuttingnd lying anterior to the flexor tendon. The mass

easured 2.4 (length) � 1.2 (anteroposterior) � 1.5 b

024 The Journal of Hand Surgery

width) cm. The mass was lobulated and of interme-iate signal intensity on both T1- and T2-weightedmaging (Fig. 3). There was also evidence of a fewnternal fatty septations and tiny speckled areas ofow signal corresponding to the punctate calcificationresent on the plain films.Differential diagnosis of this soft-tissue mass in-

luded benign lesions such as a soft-tissue chon-roma and giant cell tumor (GCT) of the tendonheath. Less likely this mass could represent a ma-ignant process such as a soft-tissue sarcoma. Be-ause of the slow-growing nature and benign radio-raphic appearance of the mass we elected to proceedith excisional biopsy. Under general anesthesia and

ourniquet a longitudinal incision was made, showingn encapsulated mass that was not adherent to thekin but adherent to the surrounding fatty and fibrousissue. The mass was rising from the flexor sheathnd the fascia over the interosseous muscles. Theortion of the flexor sheath was excised progres-ively, incorporating the mass and the fascia over theadial lumbrical until the mass was excised com-letely (Fig. 4). Intraoperative frozen section showedcalcified aponeurotic fibroma. Margins were ex-

ised until free from tumor, leaving the tendon un-overed from the proximal end of the A2 pulley areao the palmar region. The postoperative course wasnremarkable.

iscussionalcified aponeurotic fibroma is a rare benign soft-

issue tumor with intermediately aggressive bio-ogic behavior. Now classified within the group ofuperficial musculoskeletal fibromatosis1 these le-ions first were described in 1953 by Keasbey2 asalcifying juvenile aponeurotic fibromas becausehey were believed to occur only in the first andecond decades of life. Now over 80 cases have

een described in the literature3; the mean age of

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Parker, Beckenbaugh, and Amrami / Calcified Aponeurotic Fibroma Differentiation 1025

nset is 12 years but there are documented casesrom birth4 to 64 years.5

These tumors have a predilection for the palms,ngers, and soles of the feet,2 with males affectedore than twice as commonly as females.5 The

Figure 1. Photographic views of the le

igure 2. Radiographs of the left hand. (A) The anteroposterioth MCP interspace. (B) On lateral view the mass is visible wit

atrix (arrow).

ypical presentation is that of a slow-growing,symptomatic mass. It has been reported that 67%f these arise in the deep palmar fascia of theand.5,6 They rarely measure more than 3 cm iniameter and have never been reported as being

mass. (A) Anteroposterior, (B) lateral.

demonstrates a soft tissue density centered over the 4th andence of multiple punctate densities suggestive of a chondroid

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1026 The Journal of Hand Surgery / Vol. 31A No. 6 July–August 2006

dherent to skin or associated with joint contrac-ures.7

The recurrence rate after surgical excision iseported generally as 50%6 and the tumor-freenterval ranges from 6 months to 23 years.5,8,9 Thisecessitates an accurate diagnosis and completexcision. Gross pathology is that of a flesh-coloredobulated mass with pseudoencapsulation or annfiltrative margin. Microscopically the tumors areomposed of spindle-shaped fibrous cells that areeparated and surrounded by abundant collagenaterial with rare mitoses.1 Diffuse background

igure 3. High-resolution magnetic resonance images (MRI)nhancing soft-tissue mass at the ventral base of the fifth mendon. The lobulated mass demonstrates a few internal fattyhe punctate calcification present on the plain films.

igure 4. Intra-operative photographic views of the left palmhat was not adherent to the skin but adherent to the surrounnd the fascia over the interosseous muscles. (B) The portion

ass and the fascia over the radial lumbrical until the mass was e

taining with S-100 protein is thought to be non-pecific, although definite staining for smooth-uscle actin and other elements is noted on Mas-

on trichrome staining.7 Scattered foci ofhondroid differentiation are a distinguishing fea-ure.5,10 Recently, cytologic features have beeneported11 and suggest that diagnosis with fine-eedle aspiration biopsy is possible to aid in dif-erentiation from soft-tissue sarcomas.

Radiographs show a nonspecific soft-tissue masshat may show finely stippled calcifications and oc-asional scalloping of the adjacent bone.2,6,12 Calci-

hand T1- (A) and T2- (B) images show a heterogeneouslypophalangeal joint abutting and lying anterior to the flexortions and tiny speckled areas of low signal corresponding to

. (A) A longitudinal incision exposed an encapsulated massfatty and fibrous tissue. It was arising from the flexor sheathe flexor sheath was excised progressively, incorporating the

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Parker, Beckenbaugh, and Amrami / Calcified Aponeurotic Fibroma Differentiation 1027

cation observed radiologically, however, is not aonsistent feature11 and can complicate the diagnosisnd raise the suspicion of other benign soft-tissue oralignant tumors. Moreover 2 patients12,13 with

nique bony involvement have been reported.Magnetic resonance imaging may show a lobu-

ated soft-tissue mass with adherence to surroundingtructures. Prominent low to intermediate signal in-ensity and bands of low signal intensity representingighly collagenized tissue is characteristic of fibro-atosis on T1 images.1

Magnetic resonance imaging of our patient ledo a differential diagnosis of benign soft-tissueumors including hemangioma, soft-tissue chon-roma, or a GCT of the tendon sheath and lessikely a malignant process such as a soft-tissuearcoma. Giant cell tumor of the tendon sheath ishe second most frequent hand tumor, typicallyound in the fingers in the second to fourth de-

igure 5. A sagittal MRI of our patient illustrates distinguish-ng characteristics of a calcified aponeurotic fibroma, includ-ng heterogeneous enhancement, speckled calcifications,nd ill-defined margins.

ades. These are painless, lobulated masses that r

ay interfere with function. These tumors are as-ociated intimately with the tendon sheath, arisingrequently at the level of the joints. They cannfiltrate the overlying dermis14 and may erodeone by pressure15 or frank invasion.16 The pre-entation of our patient shared features of bothCT and calcified aponeurotic fibroma clinically

nd radiologically. Because of the common naturef GCT of the hand, the anatomic location of theumor in our patient, and its association with theexor tendon sheath, however, this was the pre-umed preoperative diagnosis. Careful review ofhe MRI scans showed distinguishing characteris-ics of each lesion that may have permitted the

igure 6. Giant cell tumor of the tendon sheath has a char-cteristic MRI appearance with lobulated, well-defined mar-ins; close association with the tendon sheath; and uniformnhancement after contrast administration. Pressure erosionsn adjacent bones are common but calcifications are very

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1028 The Journal of Hand Surgery / Vol. 31A No. 6 July–August 2006

rospective diagnosis of calcified aponeurotic fi-roma, including heterogeneous enhancement,peckled calcifications, and ill-defined marginsFig. 5), all of which would be more characteristicf an infiltrative fibrous lesion such as a desmoidr even aggressive fibromatosis than of GCT. Gi-nt cell tumor of the tendon sheath has a charac-eristic MRI appearance with lobulated, well-de-ned margins; close association with the tendonheath; and uniform enhancement after contrastdministration (Fig. 6). Pressure erosions in adja-ent bones are common but calcifications are veryare.

Calcified aponeurotic fibroma is a rare tumorhat presents as a painless mass primarily on theolar surface of the hands and plantar aspects ofhe feet in juveniles and must be considered in theifferential diagnosis of GCT of the tendon sheathsr sarcomas, especially in young patients. A pre-perative diagnosis based on radiographic andRI characteristics of these tumors may prevent

nnecessary biopsy, although meticulous resections advocated to prevent recurrence.

o benefits in any form have been received or will be received from aommercial party related directly or indirectly to the subject of thisrticle.

Corresponding author: Robert R. Beckenbaugh, MD, Mayo Clinic,00 1st Street, SW, Rochester, MN 55905; e-mail: beckenbaugh.robert@ayo.edu.Copyright © 2006 by the American Society for Surgery of the Hand0363-5023/06/31A06-0024$32.00/0doi:10.1016/j.jhsa.2006.04.011

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