Objective: Melanotic schwannoma is a rare neoplasm, classifiable as a peripheral nerve sheath tumor, and differentiated from a typical schwannoma by heavy pigmentation. Psammoma bodies can be visualized in more than 50% of melanotic schwannomas. Half of patients with such "psammomatous melanotic schwannomas" have Carney complex, a dominantly transmitted autosomal disorder. Most recently, the tumor suppressor gene, PRKAR1A, coding for the Type 1alpha regulatory subunit of protein kinase A was found to be mutated in approximately half of the known Carney complex families. Although cranial schwannomas have been described in patients with Carney complex, their numbers are too small to be considered a definite part of the syndrome. Furthermore, only melanotic schwannomas with psammoma bodies are included as diagnostic criteria for Carney complex. The objective of this report is to communicate a case of trigeminal nonpsammomatous melanotic schwannoma as the first manifestation of Carney complex.
Clinical presentation: A 34-year-old woman presented with odontalgia, right V3 hypoesthesia, V2 paresthesia, and diplopia. Magnetic resonance imaging scans of the brain revealed a small tumor with homogenous contrast in the right trigeminal pathway.
Intervention: We performed an extradural approach to the right cavernous sinus by a middle fossa approach. The lateral wall was opened between the cranial nerves, and a soft and black tumor was resected in a piecemeal fashion. Histology and immunohistochemical analysis of the tumor were compatible with melanotic schwannoma, but no psammomatous bodies were identified. Endocrine evaluation showed that this patient's symptoms fulfilled the diagnostic criteria of Carney complex, with lentiginosis, multiple breast ductal adenomas, multiple hypoechoic nodules on thyroid ultrasonography, and a 4 x 5-cm asymptomatic atrial cardiac myxoma, which was removed 15 days after the neurosurgery. Three months later, a recurrence of melanotic schwannoma was identified. Molecular analyses of genomic and somatic deoxyribonucleic acid from the patient found a 578 to 579delTG mutation of PRKAR1A.
Conclusion: We present the unusual case of a nonpsammomatous trigeminal melanotic schwannoma associated with Carney complex, with confirmed PRKAR1A gene mutation. Our case highlights that neurosurgeons, in the presence of a melanotic schwannoma, should be aware of the features of the Carney complex because, in such cases, pre- and postoperative management is significantly affected. We also postulate that the absence of psammoma bodies or cranial localization do not exclude this diagnosis.