Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor that primarily affects children, adolescents, and young adults. It is considered low-grade, meaning it rarely spreads to distant sites. Despite its name, AFH is not typically cancerous, as it rarely metastasizes.
What is Angiomatoid Fibrous Histiocytoma?
Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue neoplasm, accounting for about 0.3% of all soft tissue tumors. It commonly arises in the deep dermis and subcutaneous tissue of the extremities, though it can also appear in the trunk, head, and neck. The term “angiomatoid” refers to the tumor’s characteristic appearance, often featuring blood-filled spaces, while “fibrous” describes its ropey nature.
AFH is often well-defined, with distinct nodules of cells. These nodules frequently surround blood-filled cavities. A dense cuff of inflammatory cells typically surrounds the tumor. The World Health Organization (WHO) classifies AFH as a tumor of intermediate biological potential, meaning it has a low risk of metastasis but can locally recur.
Recognizing the Signs
AFH presents as a slowly growing, often painless lump or mass under the skin or in deeper soft tissues. The mass is usually firm and may be movable. While often without symptoms, some individuals might experience localized pain or tenderness, especially if it presses on surrounding nerves or structures.
Less common symptoms include discoloration of the overlying skin. In rare instances, systemic symptoms like fever, anemia, or weight loss may occur, though these are not typical for most AFH cases.
Diagnosing Angiomatoid Fibrous Histiocytoma
Diagnosing AFH involves a physical examination followed by imaging studies. Ultrasound, MRI, or CT scans are commonly used to assess the tumor’s size, exact location, and its relationship to nearby tissues.
A definitive diagnosis relies on obtaining a tissue sample through a biopsy for pathological examination. Microscopic examination by a pathologist reveals the characteristic features of AFH, including its nodular growth pattern and blood-filled spaces. Immunohistochemistry and genetic testing are also employed to help distinguish AFH from other soft tissue tumors.
Treatment Approaches
The primary treatment for AFH is surgical removal. The goal of surgery is complete excision of the tumor with clear margins, meaning the tumor is removed along with a small amount of healthy surrounding tissue. Achieving clear margins minimizes the risk of the tumor growing back.
Chemotherapy or radiation therapy are not standard treatments for AFH due to its low-grade nature. These therapies are reserved for rare cases where the tumor is aggressive, has spread, or recurs multiple times and is difficult to remove surgically. Following surgical excision, regular follow-up appointments are recommended to monitor for any signs of recurrence.
Understanding the Outlook
The prognosis for AFH is generally favorable, especially after complete surgical removal. While the tumor can recur locally, with reported rates ranging from approximately 11% to 23%, these recurrences are typically manageable with further surgical intervention. Close follow-up is recommended to detect any recurrence early.
Distant metastasis, or the spread of AFH to other parts of the body, is uncommon, occurring in less than 5% of cases. When metastasis does occur, it most commonly involves regional lymph nodes, though spread to other organs is rare. The overall course of the disease is typically benign, and most patients experience a positive long-term outlook.