TABLE 11.1 Immunohistochemical Profiles of Spindled Cell Neoplasms of the Upper Aerodigestive Tract
TABLE 11.2 Fibroblastic/Myofibroblastic Lesions of the Upper Aerodigestive Trace
young adults. Clinically, they present as rapidly enlarging, solitary, and often tender masses and are usually less than 2 cm in size. The lesions do not recur if they are completely resected. They are now considered neoplastic and characteristically have MYH9-USP6 translocations.11
tumors in small biopsy specimens may be impossible. Inflammatory myofibroblastic tumors can appear more inflamed and have more sclerotic areas; however, they often have areas very reminiscent of nodular fasciitis. Clinical history and immunostaining with antibodies to ALK1 (see below) may be helpful. Identifying a USP6 translocation, usually with break-apart FISH, can clinch a diagnosis.11
fibromatoses are infiltrative and fascicles of spindled myofibroblasts can be seen dissecting through adjacent soft tissues. Frequently, entrapped skeletal muscle can be seen with degenerating changes, and it is important not to confuse these changes with epithelial or multinucleated giant cells (Fig. 11.9, eFig. 11.9). Occasional mitotic figures may be present; however, more than mild cellular or nuclear atypia should exclude the diagnosis.
FIGURE 11.8 Bland spindled cells and abundant collagen seen in a case of extra-abdominal fibromatosis.
FIGURE 11.9 Entrapped, degenerating skeletal muscle cells in a case of extra-abdominal fibromatosis.
have oval, rounded, or tapered nuclei with vesicular chromatin and small, indistinct nucleoli (Fig. 11.11). The tumors often have hypocellular and hypercellular areas with many small slitlike vessels. In the more cellular areas, the vessels may display a hemangiopericytoid appearance often with the intravascular polypoid projection of tumor (eFig. 11.10). Occasional mitotic figures may be noted (up to 5 per 10 high-powered fields). Despite their gross appearance of circumscription, infiltration of surrounding tissue is usually present with entrapped soft tissue elements (e.g., peripheral nerved or skeletal muscle) (eFig. 11.11). Multinucleated giant cells can be present, as can degenerative myxoid changes and necrosis (eFigs. 11.12 and 11.13). Some cases have abundant stromal collagen.
upper aerodigestive tract are found to be much less common than they were once believed to be. Nonetheless, small series have been published of these tumors within the sinonasal area and the mouth, while a few scattered case reports have described these tumors in the larynx.24,25,26,27,28,29 The tumors arise submucosally in adults of either sex and may either appear as lumps or as polypoid masses. Solitary fibrous tumors are mostly benign, but some (10%-15%) will behave aggressively and may recur or even metastasize.30 Most tumors have a NAB2-STAT6 translocation.31
FIGURE 11.12 A solitary fibrous tumor of the nasal cavity with numerous spindled cells and entrapped collagen.
FIGURE 11.14 An inflammatory myofibroblastic tumor of the larynx with a cellular appearance somewhat akin to nodular fasciitis.
to be unique to inflammatory myofibroblastic tumors.43 The large spindled cells with eosinophilic cytoplasm may occasionally appear reminiscent of the rhabdomyoblasts or strap cells seen with embryonal rhabdomyosarcomas. Cross striations and less differentiated areas should not be seen with inflammatory myofibroblastic tumors nor should immunoreactivity with antibodies to myogenin. The characteristic inflammatory cell infiltrate seen with inflammatory myofibroblastic tumors is not usually seen with embryonal rhabdomyosarcomas.
are spindled and have pale, eosinophilic cytoplasm with tapered nuclei (eFig. 11.24). The nuclei have fine or vesicular chromatin and inconspicuous nucleoli. Most cases have little atypia, although occasional examples display moderate atypia with enlarged, pleomorphic, hyperchromatic nuclei and prominent nucleoli. Occasional stellate cells with elongated cell processes may be seen. Mitotic activity is present and up to 10 mitotic figures per 10 high-powered fields have been found. Tumor necrosis may is noted focally in rare cases.
FIGURE 11.18 A low-grade myofibroblastic sarcoma with infiltration into surrounding skeletal muscle.
especially monophasic synovial sarcomas and malignant peripheral nerve sheath tumors, need to be distinguished from these malignancies. This can usually be accomplished with immunohistochemistry (Table 11.1). Adult fibrosarcomas typically have limited cellular atypia, and more pronounced
atypia should lead to a diagnosis of pleomorphic sarcoma. Finally, as with all spindle cell sarcomas of the upper aerodigestive tract, these tumors need to be distinguished from sarcomatoid carcinomas, especially after radiation therapy for squamous cell carcinoma. Intraepithelial neoplasia (squamous dysplasia) or focal squamous differentiation can often be identified with sarcomatoid carcinomas, and many sarcomatoid carcinomas show immunoreactivity with antibodies to cytokeratins.
to diagnose the lesion as a sarcomatoid carcinoma. Dedifferentiated liposarcomas and chondrosarcomas as well as osteosarcomas should be distinguished from these lesions because of their different prognoses, and a careful search for well-differentiated liposarcoma or chondrosarcoma or
osteoid production should be made. Immunohistochemistry can be used when needed to distinguish leiomyosarcomas and angiosarcomas from these tumors.
FIGURE 11.21 A storiform growth pattern and moderate cellular atypia is seen with this undifferentiated high-grade pleomorphic sarcoma of the tongue.
vary greatly in size, and a single tumor that was only 3 mm in greatest dimension has been reported.66 Histologically, the tumors are infiltrative rather than circumscribed. They are composed of fascicles of spindled cells with eosinophilic cytoplasm; however, cytologic features of malignancy are also seen, with cellular and nuclear atypia, increased mitotic activity, and tumor necrosis (Fig. 11.25, eFig. 11.36). Smooth muscle differentiation should be identified by immunohistochemistry. Leiomyosarcomas metastasize in more than 50% of the patients affected, and nearly one-third of these patients may die of their disease.