Case # 95-4
History/Physical Findings:
A 54-year-old healthy male presented to a dermatologist with a 2 cm
rapidly-growing (first noticed less than a month prior to to
presentation) subcutaneous forearm nodule. The nodule was firm and
freely mobile and was excised.
Pathology:
Gross:
A 2.5 x 1.5 x 0.5 cm smooth and largely circumscribed gray to white
ovoid mass with fragments of attached adipose tissue. The cut surface
was firm and fibrous.
Microscopic:
 
Figure 1 (low power): There is a well-circumscribed nodule composed
of spindled cells within a collagenous and myxoid matrix, with attached
fragments of fibroadipose tissue.
Figure 2 (high power): There are spindled fibroblast-like cells
embedded in a loose fibromyxoid matrix, as well as other cells with
abundant basophilic cytoplasm, resembling ganglion cells. Occasional
binucleate cells are seen. Mitotic figures are rare.
Based on the above findings, what is your diagnosis?
Discussion:
The history of a rapidly-growing superficial nodule in a middle-aged
person, usually on an extremity, in combination with the histologic
findings described, is characteristic of proliferative fasciitis, which
is considered by many to be a variant of nodular fasciitis. These are
self-limiting, benign reactive processes whose etiology is unknown.
Their development is sometimes preceded by soft tissue trauma. Complete
excision is almost always curative, with local recurrence rare.
Nodular fasciitis is generally considered to be more circumscribed
than proliferative fasciitis and lacks the plump ganglion-like cells
characteristic of the latter. Both may occur in subcutis, muscle, or
fascia. The cells of nodular or proliferative fasciitis are
immunoreactive for vimentin, smooth muscle actin and muscle-specific
actin, but negative for desmin or S-100 protein.
The differential diagnosis is wide. The lesion may be misdiagnosed
as fibrosarcoma. The cells in the latter are usually densely packed in
classic “herringbone” fashion and demonstrate more nuclear pleomorphism
and hyperchromaticity, with numerous mitotic figures. Myxoid malignant
fibrous histiocytoma usually occurs in patients over 50 and presents as
a larger, deeper mass. The nuclei of MFH cells are strikingly
pleiomorphic.
Diagnosis:
Proliferative fasciitis
References:
- Enzinger FM, and Weiss SW (1995). Soft Tissue Tumors. Mosby, St.
Louis. pp. 165- 199.
- Lundgren L, Kindblom L-G, Willems J, Falkmer U, and Angervall L
(1991). Proliferative myositis and fasciitis. A light and electron
microscopic, cytologic, DNA- cytometric and immunohistochemical study.
APMIS 100:437-448.
Contributors:
James Mandell, M.D., Ph.D.
Department of Pathology
University of Virginia Health System
Philip H. Cooper, M.D.
Department of Pathology
University of Virginia Health System
Questions should be addressed to
dji@virginia.edu
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