Sarcomas of Fibrous Tissue

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Fibrosarcoma is a rare malignant tumor from deep tissues such as fascia or tendons. Well-established causative factors include ionizing radiation (204), chronic scars, and certain chromosomal aberrations. Fibrosarcoma affects all ages but is more common during the fourth to sixth decade of life. Tumors present clinically as subcutaneous masses with intact overlying skin. Ulceration indicates aggressive growth. Pain is present in 50% of cases. Approximately 50% of lesions occur on the lower extremity with marked predominance of the thigh (205). On histopathological examination, there are masses of spindle cells with variable differentiation, storiform pattern, and myxoid changes. IHC stains are positive for CD34 and vimentin, but not for epithelial, muscular, neural, melanocytic, or vascular markers (see below). Treatment is similar for all soft tissue sarcomas. Wide local excision with or without amputation is the usual approach. Adjuvant radiation therapy is indicated for aggressive or invasive cases. Recurrence rates are unknown but 5 year survival is 50%. Current protocols also include chemotherapy with doxorubicin but the survival rate has not been modified (206).

Dermatofibrosarcoma protuberans (DFSP) is an uncommon soft tissue tumor accounting for fewer than 0.1% of all malignancies and 1% of soft tissue sarcomas. This tumor arises in the dermis and invades the surrounding tissue by radial and vertical extension through the pre-existing collagen bundles and along connective tissue septa. Fifty percent of these neoplasms arise on the trunk, 35% involve the extremities, and 15% occur on the head and neck. DFSP has been reported in all races with a slight predominance in men (207). Most cases occur in patients between ages 20 -c and 50 years. Twenty percent of all patients report antecedent trauma. This tumor ^

o has also been reported to arise in surgical scars, vaccination scars, and burn scars. Tumors may appear as a plaque or nodular growth. The initial presentation is |

usually a dusky, indurated plaque that may go unrecognized for an extended period o of time. The color of the plaque may vary from brown to bluish-red with a blue or §

reddish hue of the surrounding skin. The plaque is usually flat and in some cases

Dermatofibromas
Figure 34 Dermatofibrosarcoma protuberans on the ankle of a young man. The lesion is firm, brown, and well-demarcated. DFSP lesions may be clinically identical to keloid scars or dermatofibromas.

depressed, resembling morphea, and over time the plaque becomes larger with the gradual development of a nodular component within the sclerotic area. The nodular component may become quite large in advanced tumors and vary in color from flesh-colored to dusky red or red-brown (Fig. 34). Five percent of DFSPs may present as a rare variant known as a Bednar tumor. This pigmented form occurs predominantly in black patients and contains melanin. Histologically, DFSP is composed predominantly of cells with large, spindle-shaped nuclei embedded in varying amounts of collagen. The cells are arranged in irregular, intertwining bands producing a storiform or matlike pattern (Fig. 35). IHC staining is positive for CD-34 (208). Surgical excision is the treatment of choice. Recurrences are common because the infiltrating growth pattern often extends well beyond the perceived clinical margins. Reported rates of recurrence vary from 11 to 54% following treatment with conventional surgical excision (209). Mohs' micrographic surgery along with rapid immunohisto-chemical staining for CD-34 antigens is useful in the surgical management of DFSP. More than 200 cases have been treated to date with only seven recurrences (3.3% recurrence rate) (210). Radiation therapy is indicated for inoperable tumors |

and as an adjunct to surgical removal. However, it should be used cautiously because fibrosarcomatous changes within DFSP have been reported following irradiation. Chemotherapy plays no role in the treatment of DFSP. DFSP metastasizes in fewer d than 4% of cases. Metastatic cases almost always are recurrent tumors with a considerable time elapsed between diagnosis, multiple recurrences, and metastasis. Favored metastatic locations include lung, brain, bone, and, rarely, lymph nodes.

Atypical fibroxanthoma (AFX) is a fairly common tumor that presents predominantly on the sun-exposed areas of the head and neck regions of elderly

Figure 35 Characteristic storiform arrangement of spindle cells in dermatofibrosarcoma protuberans. A rare variant containing large amounts of melanin is known as the Bednar tumor.

patients. The most common locations are the nose, cheek, and ear with occasional occurrences on the trunk and limbs. This tumor usually presents as an asymptomatic solitary nodule or ulcerating nodule 2 cm in diameter or smaller. Clinically, AFX may resemble squamous cell carcinoma, basal cell carcinoma, epidermal inclusion cyst, or an ulcerated pyogenic granuloma. UV radiation appears to play an etiologic role since many of these tumors occur on severely actinically damaged skin in elderly individuals. Radiation therapy is also thought to be a contributing factor (211). AFX is often considered a superficial form of malignant fibrous histiocytoma. Due to its superficial location within the skin and its relatively small size, the tumor usually pursues a benign course. It has rarely been reported to metastasize to regional lymph nodes and parotid gland. On histological examination, AFX is composed of cells with pleomorphic, often hyperchromatic, nuclei in an irregular arrangement. Cells may appear spindle-shaped and lie in small bundles resembling fibroblasts. Other cells may appear polygonal and have foamy vacuolated cytoplasm and thus resemble histiocytes. Most AFX tumors will have large, bizarre, multinucleated giant cells showing marked nuclear atypicality. Recommended treatment for cutaneous AFX

is surgical excision with margin control. Mohs' micrographic surgery has been used ^

d to treat AFX with excellent clinical results (212). Nodal disease is approached with >3

surgical excision of the primary site and lymph node dissection. Adjuvant radiation therapy has been successfully employed in some cases.

Malignant fibrous histiocytoma (MFH) is a pleomorphic sarcoma representing §

the most common soft tissue sarcoma of middle and late adult life. It is an aggressive soft tissue sarcoma that has been subclassified into superficial and deep tumor types. Superficial tumors originate in the subcutaneous tissue and attach to the underlying fascia. In rare cases these tumors may invade the overlying dermis, resulting in ulceration. The deep tumor variety may originate in the subcutaneous tissue and extend through the underlying fascia into the muscle, or may originate within the muscle itself. The deep tumor variety appears to be twice as common as the superficial type, with poorer survival. Metastases occur in regional lymph nodes and the lungs and are the usual cause of death (213). On histological examination, MFH is a highly cellular tumor made up of fibroblastic, histiocytic, and bizarre-appearing cells. Fibroblastic cells have elongated-to-spindle-shaped nuclei and are arranged in storiform patterns. Histiocytic cells have a polygonal structure with irregularly shaped nuclei and cytoplasm that may be eosinophilic or vacuolated. Multinucleated giant cells with bizarre, hyperchromatic nuclei can be noted. IHC stains are positive for vimentin (mesenchymal); lysozyme, alpha-1 antitrypsin, and CD-68 (histiocytes); and collagen- and fibroblast-associated antigen (fibroblasts). Surgical excision with or without regional lymph node dissection is the treatment of choice. Reported recurrence rates are 30-47% even after amputation. Adjuvant radiation lowers the recurrence rate to 19% (214). Mohs' micrographic surgery can be used for the superficial type of MFH. A retrospective study involving 17 patients demonstrated a single recurrence after an average of 3 years' follow-up. Overall 5 year survival is 70% (215). The metastatic rate is variable depending on the depth of invasion. MFH confined to the subcutaneous tissue metastasizes in fewer than 10% of cases; those involving the subcutaneous and fascial planes have a metastatic rate of 27%. Deep-seated tumors involving skeletal muscle metastasize in 43% of cases. The 5 year survival rate is approximately 60%.

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