Inflammatory myofibroblastic tumor of the central nervous system and its relationship to inflammatory pseudotumor

Pulmonary pseudoneoplasms

CONTEXT

Not uncommonly, a surgical pathologist will be requested to review excised material, with a clinical diagnosis of cancer, in which no malignancy can be identified. Often, sampling may be the issue. However, different nonneoplastic processes may mimic cancer clinically and not be recognized histologically. These are commonly referred to as pseudoneoplasms and can involve the lung, pleura, and mediastinum.

OBJECTIVE

To review the most commonly encountered pseudoneoplasms of the thoracic cavity in surgical pathology and discuss the main differential diagnosis.

DATA SOURCES

Literature and personal review of cases with focus on inflammatory pseudotumors of the lung, organizing pneumonia, nodular lymphoid hyperplasia, apical cap, round atelectasis, and sclerosing mediastinitis with its pulmonary counterpart, hyalinizing granuloma.

CONCLUSIONS

When reviewing specimens that appear nondiagnostic for malignancy, it is important to consider one of these pseudoneoplasms in the differential diagnosis as they may explain the clinical and radiologic information.

Pseudoneoplasms of the Nervous System

Context.—Pseudoneoplasms of the nervous system vary greatly in nature. Ranging from inflammatory to autoimmune, infectious, malformative, reactive, degenerative, and radiation induced, they all mimic true tumors. Thus, they have the potential to mislead clinicians, radiologists, and pathologists alike. Their clinical and/or neuroimaging and histologic features are readily misinterpreted as tumor. Knowledge of the pitfalls is essential to avoid mismanagement, specifically overtreatment. In such instances, pathologists must take the entire clinical picture into consideration, acquainting themselves with presenting symptoms, physical findings, and neuroimaging.

Objective.—To present 10 examples of pseudoneoplasms of the nervous system, analyze the basis for their mimicry, and discuss their differential diagnosis.

Data Sources.—Review of the pertinent literature related to pseudoneoplasms of the nervous system and review of the consultation files of one of the authors (B.W.S.).

Conclusions.—The identification of tumor mimics may be difficult under the best of circumstances, and maintaining a broad differential diagnosis as well as application of a variety of immunocytochemical and occasionally ultrastructural and/or molecular genetic methods is essential to arrive at a correct diagnosis.

Clinical and cytogenetic analysis of an intracranial inflammatory myofibroblastic tumor induced by a ventriculoperitoneal shunt

The authors report the first case of an intracranial inflammatory myofibroblastic tumor (IMT) associated with the placement of a ventriculoperitoneal shunt, which occurred in a 7-year-old boy. Neuroradiological features showed a mass surrounding the ventricular catheter. The lesion was completely resected. Histological study revealed the mass to be an IMT. The patient's postoperative course was complicated by a local recurrence requiring a second surgery. Cytogenetic analysis of the sample by comparative genome hybridization revealed several chromosomal amplifications and regional losses. The occurrence of IMT in the CNS has rarely been reported. For treatment of this condition, the authors recommend a total removal of the shunt with a mass excision to prevent local recurrence.

Anaplastic lymphoma kinase: role in cancer pathogenesis and small-molecule inhibitor development for therapy

Anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase in the insulin receptor superfamily, was initially identified in constitutively activated oncogenic fusion forms - the most common being nucleophosmin-ALK - in anaplastic large-cell lymphomas, and subsequent studies have identified ALK fusions in diffuse large B-cell lymphomas, systemic histiocytosis, inflammatory myofibroblastic tumors, esophageal squamous cell carcinomas and non-small-cell lung carcinomas. More recently, genomic DNA amplification and protein overexpression, as well as activating point mutations, of ALK have been described in neuroblastomas. In addition to those cancers for which a causative role for aberrant ALK activity is well validated, more circumstantial links implicate the full-length, normal ALK receptor in the genesis of other malignancies - including glioblastoma and breast cancer - via a mechanism of receptor activation involving autocrine and/or paracrine growth loops with the reported ALK ligands, pleiotrophin and midkine. This review summarizes normal ALK biology, the confirmed and putative roles of ALK in the development of human cancers and efforts to target ALK using small-molecule kinase inhibitors.