Tumoren dendritischer und anderer akzessorischer Zellen der Lymphknoten

[Differential diagnosis of reactive cytopenias]

Reactive cytopenias are a frequent cause for bone marrow investigations, including bone marrow trephine biopsies, especially if clinical examination and laboratory analyses (e.g., detection of substrate deficiencies) cannot provide a sufficient explanation. The evaluation of such biopsies is primarily concerned with the exclusion of diseases that displace the normal hematopoiesis (infiltrates of acute leukemias or lymphomas and metastases), the exclusion of a myelodysplastic syndrome that classically results in ineffective hematopoiesis, or the detection of specific diseases, particularly infectious or histiocytic diseases (e.g., hemophagocytic lymphohistiocytosis).In this review, we describe characteristic morphologic changes of reactive cytopenias, focus on specific infectious and noninfectious clinical pictures, and distinguish them from malignant changes, especially myelodysplastic syndrome and underlying leukemia of large granular T lymphocytes. Drug-induced changes in hematopoiesis are described in another article in this issue.

An Unusual Bump on the Head: Intracranial and Extracranial Cytokeratin-Positive Interstitial Reticular Cell Tumor

BACKGROUND

We describe a cytokeratin positive interstitial reticulum cell tumor (CPIRCT) as the cause of a large and defacing scalp tumor. Clinically these tumors manifest as progressive, painless swelling. Treatment usually consists of surgery with or without irradiation; chemotherapy is applied in metastatic disease.

CASE DESCRIPTION

A patient was referred after attempted removal of a large bump on the head. The tumor was initially noted about 12 months earlier. Assuming a benign lipoma, resection without prior imaging was attempted. During surgery, the underlying bone was found to be profoundly destroyed. Cranial magnetic resonance imaging revealed a large mass with an extracranial and intracranial component. Subsequent extensive resection finally led to the diagnosis of CPIRCT.

CONCLUSIONS

Most CPIRCTs manifest as progressive palpable or visible masses. Radical excision is usually the mainstay of treatment, although there is no generally accepted treatment strategy. A needle biopsy might not be diagnostic and can complicate future curative surgery. Especially in fast-growing lesions, imaging studies should be considered before surgery. Their potential recurrence and metastatic spread render CPIRCTs an interdisciplinary challenge and highlight the need for long-term follow-up.

A pattern-based approach to reactive lymphadenopathies

A crucial task in histopathological examination of enlarged lymph nodes is to discriminate malignant form benign processes. The central importance of this issue is reflected by the fact that benign lymphadenopathies mistaken for lymphomas belong to the most commonly misdiagnosed cancers. In addition, recognition of distinct histopathological patterns of reactive lymph node changes narrow down the potential number of causative agents, especially of those that can be specifically identified by means of often very resource-consuming ancillary techniques; thus, the more precise the differential diagnosis established upon histopathological examination is, the more targetable and efficient the application of these techniques will be. This review provides a synopsis on a histopathological pattern-based approach towards reactive lymphadenopathies.