Histiozytäre Erkrankung des Kindes- und Jugendalters

The postnatal development of the compartments in human lymph nodes up to 15 years of age

The postnatal development of normal human lymph nodes (LN) is largely unknown but is of relevance for intranodal desensitization and for comparison to lymphoma. Superficial inguinal lymphoid (LN) of 25 children (newborn up to 14 years) were studied by routine histology and immunohistology for T and B lymphocytes. The LN were obtained from the legal medicine department at necropsy. The cortex and medulla were identifiable in LN of children of less than 1 month of age. Later high endothelial venules as typical structures for the T cell area are present. Secondary follicles were obvious from 3 months of age onwards in lymph nodes of adolescents also the histology of the LN was similar to adults. The structural elements for an intranodal desensitization are given in human children. The normal development of LN structure is essential to identify pathology like lymphoma in children.

Histiocytic and Dendritic Cell Neoplasms

Histiocytic and dendritic cell neoplasms are very rare, belonging to a group that share morphologic, immunophenotypic, and ultrastructural characteristics of mature histiocytic/dendritic neoplasms. Histiocytic and dendritic cell neoplasms may arise de novo or in association with B-cell, T-cell, or myeloid neoplasms. Recent molecular findings, particularly the discoveries of the mutations in the RAS-RAF-MEK-ERK pathway, have greatly advanced the diagnosis and treatment options. Histiocytic and dendritic cell neoplasms may closely resemble each other, non-hematopoietic neoplasms, and even reactive processes. Therefore, it is essential to understand the clinicopathologic characteristics, differential diagnoses, and pitfalls of each entity.

[Non-neoplastic lesions of the mediastinum]

The mediastinum is a complex body region of limited space but containing numerous organs of different embryonic origins. A variety of lesions that are difficult to distinguish from each other can occur here. Non-neoplastic lesions of the mediastinum represent important differential diagnostic pitfalls to mediastinal tumors, clinically, radiologically and histopathologically. It is important to bear these lesions in mind and to adequately verify or exclude them before starting further differential diagnostic considerations on mediastinal neoplasms. The most common non-neoplastic lesions in this region include cysts and lymphadenopathies. Mediastinal cysts result from abnormal events in the branching of the tracheobronchial tree, the pharyngeal pouches, the primary intestines, the pleuropericardial membranes and the brain meninges or are complications of inflammatory and hydrostatic processes. The histogenesis of the lining epithelium and the cyst wall structure are decisive for the exact classification. The histopathologically most prevalent patterns of mediastinal lymphadenopathies are those accompanied by increased histiocytes and Castleman's disease. Sclerosis is a non-specific reaction pattern of the mediastinum and can be associated with many processes; therefore, when establishing the diagnosis of sclerosing mediastinitis, several differential diagnoses have to be excluded. Simple thymic hyperplasia can be accompanied by considerable increase in organ size with severe local symptoms, while follicular thymic hyperplasia is often associated with myasthenia gravis and represents the most common findings in non-thymoma thymectomy specimens.

Redefining the Prevalence of Dural Involvement in Rosai-Dorfman Disease of the Central Nervous System

BACKGROUND

Sinus histiocytosis with massive lymphadenopathy, also known as Rosai-Dorfman disease, is a rare condition, classically characterized by painless, massive cervical lymphadenopathy. Histologically, the pathognomonic findings include a dense, mixed inflammatory infiltrate with areas of emperipolesis. Albeit infrequent, when Rosai-Dorfman disease affects the central nervous system, it typically manifests as an isolated dural lesion, often mimicking a meningioma. A purely intraparenchymal manifestation of Rosai-Dorfman disease of the brain and spine with absent dural involvement is exceedingly rare.

CASE DESCRIPTION

In this report, we describe a 59-year-old woman who underwent surgical excision of an intraparenchymal cerebellar lesion. Histologic analysis of the resected specimen diagnosed isolated Rosai-Dorfman disease with absent systemic involvement. We also provide an updated review of the literature of nondural-based Rosai-Dorfman disease in the central nervous system.

CONCLUSIONS

With the recent increase of such reported cases, it becomes imperative that Rosai-Dorfman be considered more than as a dural lesion that may mimic meningioma. Diagnostic and therapeutic challenges surrounding this disease entity are also discussed.