INTRODUCTION: Papillary carcinoid tumor of the lung is a distinct variant of carcinoid tumors. This can often be misdiagnosed as sclerosing hemangioma. Due to the metastatic potential of carcinoid tumors, this distinction is an important one. We report a case of a papillary carcinoid tumor of the lung in a woman who presented with chest pain.
CASE PRESENTATION: A 35 year old woman initially presented to the emergency room with a complaint of chest pain. A chest CT scan was performed to rule out pulmonary embolism, and a 2.6 cm non-calcified mass was discovered in the right upper lobe. Due to a concern for lung cancer, a wedge resection and subsequent right upper lobectomy was performed. Her post-operative course was uneventful.The initial pathologic impression was a sclerosing hemangioma. The tumor demonstrated a papillary architecture with a dual cell population, consisting of lining cells overlying more nested tumor cells. Immunohistochemical staining revealed that the surface cells stained for pankeratin and TTF-1 and that the tumor cells stained positive for synaptophysin, chromogranin, and CD-56, but were negative for TTF-1. The main differential diagnosis was between sclerosing hemangioma versus papillary carcinoid tumor. Although the papillary architecture was consistent with a sclerosing hemangioma, it was felt that other morphologic characteristics, namely the nested areas with salt and pepper nuclear chromatin, prominent vascular network, and the positive immunostaining for synaptophysin, chromogranin, and CD56 (indicating neuroendocrine differentiation), indicated the diagnosis of a papillary carcinoid tumor of the lung.
DISCUSSIONS: In a patient of this age, the principal differential diagnosis of a solitary pulmonary nodule would consists of a neoplastic, inflammatory or an infectious process. Sclerosing hemangioma and pulmonary carcinoid tumor together, represent less than 5% of pulmonary tumors. Moreover, it is important to recognize the distinguishing characteristics of these two tumors. Sclerosing hemangiomas are typically benign tumors that are derived from type II pneumocytes. They frequently occur in women aged 30-50 years and present as an incidentally discovered nodule in radiographic studies. On microscopic examination they typically have a dual cell population of surface and lesional cells arranged in a papillary architecture. In immunohistochemical stains, the lesional cells typically are positive for EMA, keratin, and TTF1, but they are negative for chromogranin. Carcinoid tumors are well differentiated neuroendocrine tumors that also typically present as an incidentally discovered nodule. Five percent of tumors can metastasize to regional lymph nodes, and rarely can give rise to distant osteoblastic metastases. On microscopic examination they contain nests of uniform, bland cells with central nuclei and “salt and pepper” chromatin. Rarely, they can exhibit a papillary architecture, making them difficult to distinguish from sclerosing hemangiomas based on microscopy alone. In immunohistochemical stains, they are typically positive for keratin, chromogranin synaptophysin, CD 56, and occasionally for TTF-1. In this patient it was felt that despite the absence of TTF-1 (which may occur in carcinoid tumors), that the morphologic characteristics and presence of neuroendocrine markers supported a diagnosis of a papillary carcinoid tumor. Moreover, this tumor also lacked the hemangiomatous areas lined by cuboidal cells as typically seen in sclerosing hemangioma.
CONCLUSION: While there is considerable morphological overlap between papillary carcinoid tumor and sclerosing hemangiona, distinction is critical since these tumors have different biological behaviors.
DISCLOSURE: Simha Jagadeesh, No Financial Disclosure Information; No Product/Research Disclosure Information