Cellular angiofibroma
Cellular angiofibroma is a rare, benign tumor of superficial soft tissues that was first described by M. R. Nucci et al. in 1997. These tumors occur predominantly in the distal parts of the female and male reproductive systems, i.e. in the vulva-vaginal and inguinal-scrotal areas, respectively, or, less commonly, in various other superficial soft tissue areas throughout the body. CAF tumors develop exclusively in adults who typically are more than 30 years old.
CAF tumors are composed of bland mesenchymal spindle-shaped cells in an edematous to fiber-laded connective tissue background. Mesenchymal cells are cells in the cell lineage that includes fibroblasts, adipocytes, macrophages, mast cells, leucocytes, and the precursor cells which mature into these cell types. In 2020, the World Health Organization classified cellular angiofibroma tumors in the category of benign fibroblastic and myofibroblastic tumors.
CAF tumors rarely recur after surgical removal and do not metastasize to distant tissues. Accordingly, surgical resection is the commonly performed and current standard for treating these tumors.
Presentation
CAF tumors commonly present as painless, slowly growing, soft tissue nodules or masses in the vulva-vaginal and inguinal-scrotal areas; less commonly in the perineum; and rarely in the urethra, pelvis, anus, retroperitoneum, lumbar region, middle of the trunk, rectum, oral mucosa, knee, upper eyelid, hip, chest wall, axilla, breasts, and upper abdomen. The tumors are generally centered in the subcutaneous tissue or in the case of internal tumors, such as those located in the mouth, urethra, rectum, or anus, the submucosa. In one study of 51 individuals, these tumors had been noticed for 1 week to 5 years prior to diagnosis in women and men. Their tumors ranged from 0.6 to 25.0 cm in maximum diameter size.Pathology
, CAF tumors appear as well-circumscribed, firm to rubbery, white/tan to grayish masses some of which appear to consist of multiple lobules. Rarely, these tumors had infiltrated into adjacent muscles or other nearby tissues. As determined by microscopic analyses, CAF tumors are composed of bland spindle-shaped cells in an edematous to fibrous stromal background containing bundles of collagen fibers, small to medium-sized, thick-walled, prominently hyalinized blood vessels, and a minor component of adipose tissue. Numerous mast cells, moderate numbers of lymphocytes, and small numbers of neutrophils are scattered throughout this stroma; this stroma does not contain the multinucleated giant cells or epithelioid cells that are often found in certain other types of mesenchymal tumors. However, CAF lesions may contain scattered, abnormally-shaped cells, lipoblasts, and diffuse malignant-appearing sarcoma-like changes but these findings do not alter the prognosis of CAF as being a purely benign tumor.Immunohistochemical analyses find that the cells in CAF tumors express the CD34 protein in ~50% of cases, a smooth muscle actin protein in occasional cases, MUC1 and desmin proteins in a minority of cases, but do not express S100 or cytokeratin proteins. Most cases of CAF in females contain CAF tumor cells which express estrogen and progesterone receptors while limited studies in males reported that 3 of 3 CAF cases contained estrogen receptor-expressing tumor cells while only 1 of 3 cases contained progesterone receptor-expressing tumor cells. Detection of one or more of these protein expression patterns can help differentiate CAF from other types of mesenchymal tumors.