Challenging Metastatic Melanoma to the Lung With p40 Expression: A Diagnostic Pitfall, Case Report.

p40 immunohistochemistry is a cornerstone of histopathological examination for non-small cell lung carcinoma. p40 is an isoform of p63 and is reported to be highly specific for the diagnosis of squamous cell carcinoma. Very rare pitfalls are reported for this antibody, and p40 is typically negative in melanoma. A 66-year-old patient was admitted for multiple hemorrhagic brain tumors evocative of secondary tumors. On imaging, a 26 mm lung tumor was detected, and a biopsy of the lung tumor was performed. The tumor was stained by melanic markers and diffusely stained by p40 and p63. Molecular analysis found a somatic p.Asn581Ser (c.1742A>G) point mutation in exon 15 of BRAF and a p.Arg80Ter (c.238C>T) germline variant of CDKN2A , a predisposing mutation to melanoma. This case report highlights the importance of clinical, pathologic, and molecular correlation.

Metastatic meningiomas: an unusual clinical and pathological diagnosis with highly variable outcome.

Metastatic meningioma is a rare situation. We conducted a retrospective study from our databases and identified cases of metastatic meningioma. We report three presentations of patients with medical history of surgical removal of meningioma presenting several years later a liver tumor with bone metastasis or multiple lung tumors. These observations highlight the difficulty of the clinical and pathological diagnosis and the absence of consideration of metastatic state for histologically "benign" but clinically aggressive meningiomas in the current WHO 2007 classification of meningiomas. We also reviewed published cases of metastatic meningiomas since they are clearly distinguished from haemangiopericytoma.