Discussion:



California Tumor Tissue Registry

Case of the Month

March, 2003

“A Mature Woman With a Lump in the Neck”

A 63 y/o woman presented with a firm, painless nodule involving her posterior neck. At surgery, it was found involve the subcutaneous tissues, and to have a somewhat “ragged”, infiltrative periphery. The tumor was light grey and solid.

It microscopically consisted of an admixture of mature adipose tissue and dense, hypocellular collagen (Fig. 1, 2.) Within the collagen were scattered fibroblasts which lacked atypia (Fig. 3). Scattered entrapped nerve fibers were focally found. A delicate supporting vascular network was also seen.

Diagnosis: “Nuchal Fibroma”

Anthony R. Victorio, and Donald R. Chase, M.D.

Department of Pathology, Loma Linda University and Medical Center

Until Drs. Enzinger and Weiss included nuchal fibroma (NF) in the second edition of Soft Tissue Tumors (1988), the entity had generally been termed “collagenosis nuchae” a descriptive term for a fibrocollagenous proliferation that typically arises in the cervicodorsal region. As redefined, the tumor has a peak incidence in the third to fifth decades of life and has a slight male preponderance. Although it usually occurs in the cervicodorsal area, histologically similar cases have been described in paraspinal and interscapular regions, as well as in the extremities, the lumbosacral region, and in the buttocks.

Patients with NF usually present with a diffusely indurated superficial mass, which may be painful and sometimes inflamed. The tumor is unencapsulated, and tends to arise in subcutaneous tissue. It is grossly fibrotic, with varying amounts of incorporated fat. It microscopically consists of an admixture of fibroadipose tissue, dominated by densely collagenous fibrous elements which are hypocellular, with scattered, evenly spaced, mature fibroblasts, small thin-walled vessels, and entrapped nerve fibers. The tumor subtly infiltrates surrounding structures of the subcutis and occasionally involves superficial fascia or deep dermis.

Although it virtually never is misdiagnosed as being malignant, NF may mimic a number of benign conditions which also have abundant collagen:

• Fibrolipomas are usually encapsulated and well circumscribed, and have a greater proportion of mature adipose tissue than do NFs. And unlike NF, they virtually never incorporate entrapped nerve fibers.

• Nuchal fibrocartilaginous pseudotumor (NFP), a condition likely arising as an exuberant reparative reaction to soft tissue injury, occurs in the posterior aspect of the base of the neck where the nuchal ligament joins the deep cervical fascia. In contrast to NF, NFP is deeper, and involves fascia and/or subjacent tissues. NF is more superficial and does not maintain an association with ligamentous structures. It also lacks a cartilaginous component.

• Elastofibroma, a degenerative/reactive condition which usually involves the inferiomedial scapular region, may also mimic NF on low power. But unlike NF, it shows abundant elastic fibers that may be seen on high power, and appear as “stacks of coins” with elastic stains. Unlike NF, EF tends to arise in deeper soft tissue, not in the subcutis.

• Extraabdominal fibromatosis can be distinguished from NF by its tendency to grow in long, sweeping fascicles. But unlike NF, it rarely incorporates fat, and may be relatively hypercellular.

• Collagenous Fibroma (CF)

Need a blurb on this

In the above listing, NF deserves to be split out because it is a tumor strongly tied to several other diseases. In addition to its being linked to scleredema, diabetes mellitus, and organic solvent exposure, it is strongly associated with Gardner’s syndrome.

Gardner’s syndrome, along with Familial Polyposis Coli (FPC) and Turcot's Syndrome, falls within a category known as “Familial Polyposis Disorder”, an autosomal dominant condition caused by a mutation of the adenomatous polyposis coli (APC) gene. The three disorders have in common the colonic manifestation of potentially malignant adenomatous polyps. Their main differences lie in their extracolonic manifestations, which in the case of Gardner’s syndrome, includes soft tissue and bone tumors, such as osteomas of the skull, desmoid tumors, fibromas, lipomas, and tricholemomas.

Fibromas occurring in Familial Polyposis Syndrome have been given the term Gardner-Associated Fibromas (GAFs), and have a similar, if not identical appearance to nuchal fibroma. In fact, some soft tissue pathologists are using the designation “Gardner’s Fibroma” as a synonym/modifier for “nuchal fibroma.” The practicality of separating out NF from its mimics rests then in the strong association with familial polyposis, and the necessity of doing G.I. workups on patients, and family members who carry this diagnosis.

Suggested Reading:

1. Enzinger, FM, Weiss SW. Soft Tissue Tumors, 4th Ed. St. Lous, CV Mosby; 284-286, 2001.

2. Schiller PI, Kunte C, Sander CA, Kind P. Nuchal Fibroma. Hautarzt; 48(10):759-61, 1997..

3. Banney LA, Weedon D, Muir JB. Nuchal Fibroma associated with scleredema, diabetes mellitus and organic solvent exposure. Australas J Derm; 41(1):39-41, 2000.

4. Wehrli BM, Weiss SW, Yandow S, Coffin CM. Gardner-Associated Fibromas (GAF) in Young Patients: A Distinct Fibrous Lesion that Identifies Unsuspected Gardner Syndrome and Risk for Fibromatosis. Am J of Surg Pathol 25(5):645-651, 2001.

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