Angiofibroma of Soft Tissue: Clinicopathologic Characterization of a Distinctive Benign Fibrovascular Neoplasm in a Series of 37 Cases
Thirty-seven cases of a distinctive benign fibrovascular soft tissue tumor that may be mistaken for a low-grade sarcoma are described. There were 25 female and 12 male patients, ranging in age from 6 to 86 years (median, 49 y). The tumors presented most commonly as a slowly growing painless mass located in the soft tissues of the extremities, mainly the lower extremity, often in relationship to joints or fibrotendinous structures. Most lesions (29 cases) were well circumscribed, ranging in size from 1.2 to 12 cm (median, 3.5 cm). The microscopic appearance was remarkably consistent and was characterized by 2 components: a relatively uniform proliferation of bland, spindle-shaped cells with inconspicuous cytoplasm and ovoid-to-tapering nuclei set in a variably collagenous or myxoid stroma and a prominent vascular network composed of numerous small, branching, thin-walled blood vessels, often accompanied by medium-sized round or irregular and ectatic vessels. Mitoses (1-4/10 hpf) were occasionally observed (9 cases). Mild degenerative nuclear atypia was uncommon (5 cases). Tumor cells expressed epithelial membrane antigen at least focally in 16 of 36 cases (44%), CD34 and smooth muscle actin in 5 cases (14%), and desmin in 4 cases (11%); none expressed S100 protein. Five out of 6 cases analyzed cytogenetically showed a simple karyotype with a balanced t(5;8) chromosomal translocation. Treatment consisted of surgical resection: either simple excision (29 cases), wide excision (6 cases), or amputation (1 case). Follow-up information was available for 28 patients (range, 6 to 144 mo; mean, 51.9 mo). Most patients were alive with no evidence of disease, regardless of the status of surgical resection margins. Four patients developed local recurrence 9, 13, 36, and 120 months after the primary tumor was removed; only in 1 case was there an association with extensively positive surgical resection margins. One of these patients developed a second recurrence 2 months after the first one. None of the patients developed metastasis. The designation "angiofibroma of soft tissue" is proposed to reflect both the likely fibroblastic nature of the proliferating cells and the prominent vascularization of this benign soft tissue neoplasm.
Available from: Tadashi Hasegawa
- ") and confirmed that each case fulfilled the histologic criteria of, and had IHC results consistent with, the tumor type diagnosed. The diagnosis of STA was determined according to the characteristic histology described by Mariño-Enríquez and Fletcher . In brief, all of the STAs were well circumscribed and consisted of random and focally fascicular proliferations of bland, spindle-shaped tumor cells with an abundant collagenous to myxoid stroma and prominent, small, thin-walled branching vessels (Fig. 1A and B). "
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ABSTRACT: Soft tissue angiofibroma (STA), a recently suggested new histologic entity, is a benign fibrovascular soft tissue tumor composed of bland spindle-shaped tumor cells with abundant collagenous to myxoid stroma and branching small vessels. The lesion has a characteristic AHRR–NCOA2 fusion gene derived from chromosomal translocation of t(5;8)(p15;q13). However, morphologically similar tumors containing abundant fibrovascular and myxoid stroma can complicate diagnosis. We designed an original DNA probe for detecting NCOA2 split signals on fluorescence in situ hybridization (FISH) and estimated its utility with 20 fibrovascular tumors: four each of STAs, solitary fibrous tumors (SFTs), and cellular angiofibromas (CAFs) and three each of low-grade myxofibrosarcomas, myxoid liposarcomas (MLSs), and low-grade fibromyxoid sarcomas (LGFMSs). We also performed FISH for 13q14 deletion and immunohistochemistry staining (IHC) for estrogen receptor (ER), progesterone receptor (PgR), retinoblastoma (Rb) protein, and MUC-4 expression. Furthermore, IHC for Stat6 was conducted in the 20 cases analyzed by FISH and in an additional 26 SFTs. We found moderate to strong nuclear Stat6 expression in all SFTs, but no expression in the other tumors. Both ER and PgR expression was observed in STAs, SFTs, and CAFs. Expression of Rb protein was found in <10% of cells in all tumor types except MLS. The LGFMSs were strongly positive for MUC-4. All STAs showed NCOA2 split signals on FISH. All tumors, regardless of histologic type, had 13q14 deletion. The NCOA2 FISH technique is a practical method for confirming STA diagnosis. The combination of NCOA2 FISH and Stat6 IHC proved effective for the differential diagnosis of STA, even when using small biopsy specimens.
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ABSTRACT: Several soft tissue tumors are characterized by fibrous stroma with a conspicuous vascular component including cellular angiofibroma, nasopharyngeal angiofibroma, and solitary fibrous tumor. Recently, a distinctive fibroblastic tumor composed of bland spindle cells and a complex vascular network has been characterized morphologically and shown to harbor a recurrent t(5;8) translocation with AHRR-NCOA2 gene fusion. We report our recent experience with 2 examples of this benign tumor, the diagnosis for one of which was supported by fluorescence in situ hybridization for NCOA2 rearrangement. Identification of this tumor is important to prevent misdiagnosis as a low-grade sarcoma.
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