Pitfalls in Bone and Soft Tissue Pathology of the Head and Neck: Primary Intraosseous Rhabdomyosarcoma/FUS::TFCP2-Rearranged Spindle Cell Rhabdomyosarcoma and Transdifferentiated/Dedifferentiated/Undifferentiated Melanoma.

PURPOSE: Because of their relative rarity, bone and soft tissue lesions of the head and neck region can present a diagnostic challenge to anatomic pathologists who practice in a general surgical pathology model-while novel lesions may be unfamiliar to subspecialty head and neck pathologists.

METHODS

This review focuses on a diagnostically confounding neoplasm that arises in the bone (primary intraosseous rhabdomyosarcoma / FUS::TFCP2-rearranged spindle cell rhabdomyosarcoma) and soft tissue (trans-/de-/undifferentiated melanoma) of the head and neck region-each of which can easily be mistaken for more common entities.

RESULTS

The clinical, radiological, and histopathologic findings (including the molecular pathogenesis) of each neoplasm is discussed-along with selected differential diagnoses.

CONCLUSION

The accurate recognition of these neoplasms ensures that patients are reviewed, treated, and followed at the appropriate multidisciplinary meeting.