Purpose:We recently identified a KITexon11mutation in an anorectal melanoma of a patient who had an excellent response to treatment with imatinib.To determine the frequency of KIT mutations across melanoma subtypes, we surveyed a large series of tumors. Experimental Design: One hundred eighty-nine melanomas were screened for mutations in KIT exons 11, 13, and 17. KIT copy number was assessed by quantitative PCR. A subset of cases was evaluated for BRAF and NRAS mutations. Immunohistochemistry was done to assess KIT (CD117) expression. Results: KIT mutations were detected in 23% (3 of 13) of acral melanomas, 15.6% (7 of 45) of mucosal melanomas, 7.7% (1 of 13) of conjunctival melanomas, 1.7% (1 of 58) of cutaneous melanomas, and 0% (0 of 60) of choroidal melanomas. Almost all the KIT mutations were of the type predicted to be imatinib sensitive.There was no overlap with NRAS mutations (11.1% of acral and 24.3% of mucosal tumors) or with BRAF mutations (absent in mucosal tumors). Increased KIT copy number was detected in 27.3% (3 of 11) of acral and 26.3% (10 of 38) of mucosal melanomas, but was less common among cutaneous (6.7%; 3 of 45), conjunctival (7.1%; 1 of 14), and choroidal melanomas (0 of 28). CD117 expression, present in 39% of 105 tumors representing all melanoma types, did not correlate with either KIT mutation status or KIT copy number. Conclusions: Our findings confirm that KIT mutations are most common in acral and mucosal melanomas but do not necessarily correlate with KIT copy number or CD117 expression. Screening for KIT mutations may open up new treatment options for melanoma patients.

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Most patients do not have classic CT findings of bone erosion or extrasinus extension in the early course of IFS. We found that severe unilateral thickening of the nasal cavity mucosa was the most consistent finding on CT suggestive of underlying IFS, occurring much more frequently in immunocompromised patients with IFS than without IFS. Even though severe nasal cavity soft tissue thickening is much more common in IFS, this is a nonspecific finding that can be seen, to a lesser degree, in all forms of rhinosinusitis. Therefore, the clinician cannot rely solely on CT imaging and must maintain a high index of suspicion when evaluating immunocompromised patients to establish a prompt diagnosis. Early nasal endoscopy with biopsy and initiation of appropriate therapy are necessary to improve prognosis.

Intraoral pigmentation is quite common and has numerous etiologies, ranging from exogenous to physiological to neoplastic. Many pigmented lesions of the oral cavity are associated with melanin pigment. The differential diagnosis of mucosal pigmented lesions includes hematomas, varices, and petechiae which may appear to be pigmented. Unlike cutaneous melanomas, oral melanomas are diagnosed late and have a poor prognosis regardless of depth of invasion. As such, the clinical presentation and treatment of intraoral melanoma will be discussed. Developing a differential diagnosis is imperative for a clinician faced with these lesions in order to appropriately treat the patient. This article will focus on the most common oral melanocytic lesions, along with mimics.

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