[494] Intradermal Nodular Fasciitis – A Rare Lesion: Clinicopathologic Analysis of 21 Cases

S de Feraudy, CDM Fletcher. Brigham and Women's Hospital and Harvard Medical School, Boston, MA

Background: Nodular fasciitis, a benign myofibroblastic proliferation that occurs in the subcutaneous tissues of the upper extremities, trunk, and head and neck of young adults, is not widely recognized to arise primarily within the dermis. The purpose of this study was to examine the clinicopathologic and immunohistochemical features of a series of intradermal nodular fasciitis.
Design: Clinical and pathologic features and immunohistochemistry were evaluated in 21 cases of intradermal nodular fasciitis retrieved from consult files, in some of which a diagnosis of sarcoma had originally been suggested. Clinical follow-up was obtained from medical records and referring physicians.
Results: 11 patients were female and 10 were male, with a median age of 27.5 years (range 8-77). 9 lesions arose on the trunk, 8 on the limbs, 4 on the head and neck. Pre-operative duration ranged from a few weeks to 12 months. Tumors presented as a solitary swelling, ulcerated or bleeding mass. Grossly, the lesions were solid, nodular, rubbery, or firm and 0.7 to 3 cm in greatest dimension. Histologically, the lesions were well-circumscribed, unencapsulated tumor nodules involving the reticular dermis in 13 cases and the deeper half of the dermis with superficial extension into the subcutaneous tissue in 6 cases. The epidermis was ulcerated in 11 cases. Tumors were composed of palely eosinophilic spindle cells with plump, spindle to oval nuclei, small nucleoli and indistinct cytoplasmic borders, arranged in short intersecting bundles, which in some areas exhibited a storiform pattern, set in a microcystic myxoid stroma. In a third of the cases, occasional multinucleate giant cells of osteoclastic type were identified. 3 cases were associated with extensive stromal hemorrhage, 3 cases showed keloidal hyalinisation, and in 2 cases there was metaplastic ossification. The median mitotic index was 2 per 10 hpf (range 1 to 6 per 10 hpf). Scattered collections of lymphocytes, less often plasma cells and extravasated red blood cells and hemosiderin were present. Immunostaining for smooth muscle actin was strongly positive in 8/9 cases while S-100 and caldesmon staining were negative in all cases examined. None of the lesions has recurred or metastasized.
Conclusions: Intradermal nodular fasciitis occurs most commonly on the trunk of young adults, appears to show morphologic features similar to nodular fasciitis at conventional sites and should not be confused with sarcoma.
Category: Dermatopathology

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 104, Wednesday Afternoon

 

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