Paranasal sinus metastasis of breast cancer.

A 76-year-old woman presented with symptoms suggestive of acute sinusitis. Previously, her breast carcinoma was treated with right lumpectomy, adjuvant chemotherapy and breast radiotherapy. She remained free from recurrence for the following 8 years. After initial treatment with antibiotics, the local symptom worsened with exophthalmos, eye blindness and development of an ulceration of the hard palate. MRI showed irregular enhancement of the nasal cavity extended to the maxillary sinus and ethmoidal lamina and concomitant infiltration of the orbit and skull base. A biopsy of the palatal ulcer showed a poorly differentiated adenocarcinoma and was compared with the histology of the primary breast tumour and it was concluded for the same morphology. After discussion at the multidisciplinary team, a specific chemotherapy has been activated with an initial local response. Further surgical resection was not thought appropriate and the patient has subsequently undergone palliative radiotherapy to the right paranasal lesions to improve local disease control.

Tumor-intrinsic and -extrinsic roles of c-Kit: mast cells as the primary off-target of tyrosine kinase inhibitors.

c-Kit tyrosine kinase receptor and its ligand stem cell factor have multiple functions during development, whereas in adulthood they are mostly needed for stem cell (SC) maintenance and mast cell (MC) biology. c-Kit plays an essential tumor-cell-intrinsic role in many types of cancer, either providing the tumorigenic force when aberrantly activated or conferring stem-like features characterizing the most aggressive variants. A tumor-cell-extrinsic role occurs through c-Kit-dependent accessory cells (such as MCs) that infiltrate tumors and deeply influence their progression. c-Kit-targeted therapy with tyrosine kinase inhibitors (TKIs) may ideally work against both tumor and stromal cells. Here, we summarize the tumor-intrinsic and -extrinsic roles of c-Kit in cancer and discuss TKIs with their on- and off-targets, with a special emphasis on MCs as paradigmatic c-Kit-dependent accomplices for tumor progression.