This group of tumors are sometimes referred to as reactive pseudosarcomatous proliferations. Many arise at sites of trauma. These tumors are usually very cellular and have increased mitotic figures, characteristics shared with sarcomas. Yet, in general they follow a benign course. Clinical correlation and history of rapid growth are important in establishing the diagnosis.
HISTOPATHOLOGICAL VARIANTS CHARACTERIZATION
Fibrous Umbilical Polyp A Distinct Fasciitis-Like Proliferation of Early Childhood With a Marked Male Predominance
Sara O. Vargas, M.D.
From the Department of Pathology, Children's Hospital, Boston, Massachusetts, U.S.A.
Am J Surg Pathol 2001;25:1438-1442 Abstract quote
Benign fibrous lesions of the umbilicus have not been previously studied in a formal series. Clinical and pathologic findings were reviewed in all patients under age 19 with lesions resected from the umbilical region at Children's Hospital (Boston, MA, USA) during an 8-year period.
Fourteen lesions were characterized by a well-circumscribed dome-shaped or pedunculated dermal proliferation of moderately cellular fibrous tissue without significant inflammation. Fibroblastic cells were plump to elongate with abundant pale pink cytoplasm. In a subset of lesions, some cells showed atypia or ganglion cell-like morphology. Collagen ranged from sparse to long narrow bundles. Vascularity was sparse and the lesions were nonencapsulated. Loss of rete ridges and basket-weave hyperkeratosis was common in the overlying epidermis.
Immunostaining showed focal staining for muscle-specific actin and desmin in a subset of cases and no staining for cytokeratin, epithelial membrane antigen, CD34, or S-100. Age ranged from 3 to 18 months (mean 9 months, median 8 months). Thirteen (93%) patients were boys. Recurrence was not observed.
In conclusion, the “fibrous umbilical polyp” is a distinctive lesion of early childhood with an uncertain pathogenesis. It shows a marked predilection for boys, is not rare, and appears to represent a clinicopathologic entity. Perhaps the umbilicus, a midline defect that is normally filled by dense scar tissue after birth, contains unique fibrogenic factors responsible for the development of this distinct lesion.
SPECIAL STAINS/IMMUNOPEROXIDASE CHARACTERIZATION GENERAL
Vimentin, smooth muscle actin, desmin, S-100 protein, p53, and estrogen receptor expression in elastofibroma and nodular fasciitis.
Kayaselcuk F, Demirhan B, Kayaselcuk U, Ozerdem OR, Tuncer I.
Departments of Pathology and Plastic Surgery, Baskent University, School of Medicine, Adana Medical Center; and the Department of Orthopedic Surgery, Adana Numune Hospital, Turkey.
Ann Diagn Pathol 2002 Apr;6(2):94-9 Abstract quote
Elastofibroma and nodular fasciitis are two rare, benign soft tissue tumors. Elastofibroma is suggested to develop as a result of abnormal degeneration of elastic fibers after local trauma. Similarly, fibroblastic proliferation, which is triggered by local trauma or nonspecific inflammatory event, is suggested to play an important role in the origin of nodular fasciitis.
In this immunohistochemical study, vimentin, smooth muscle actin (SMA), desmin, S-100 protein, p53, and estrogen receptors were applied to paraffin sections of 10 elastofibroma and four nodular fasciitis specimens to learn more about their histogenesis and biological behavior. All cases with nodular fibrosis were strongly SMA and vimentin positive, while only three weakly stained with estrogen receptor antibody. There was no immunreactivity for S-100, desmin, and p53 in nodular fasciitis. However, all elastofibroma cases were stained positively with vimentin. No staining was observed with SMA, S-100, desmin, and p53 in elastofibroma.
The staining pattern of nodular fasciitis supported a myofibroblastic origin, whereas the SMA negativity in elastofibroma was correlated with fibroblastic origin.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.
Cell culture-This histologic pattern is commonly seen in these proliferations. It resembles the growth pattern of cells in tissue culture.
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