Histiocytic and dendritic cell neoplasms of the mediastinum

Abstract

In this review, we discuss a logical approach to diagnosis of histiocytic and dendritic cell lesions of the mediastinum. We break down the differential diagnosis between true neoplasms of histiocytic and dendritic cells [Rosai-Dorfman disease (RDD), Langerhans cell histiocytosis (LCH), and follicular dendritic cell sarcoma (FDCS)] versus selected neoplasms of other lineages which frequently attract non-neoplastic histiocytes or resemble them morphologically (carcinoma, melanoma, sarcoma, germinoma, mesothelioma, and lymphoma). As neoplasms in the latter category are more common, they should be stringently excluded before diagnosing a lesion in the first group, particularly given enormous differences in clinical management. We also consider histiocytic sarcoma (HS), an extremely rare lesion which, in some cases is likely of intrinsic histiocytic differentiation, whereas in others represents clonal evolution from an underlying non-histiocytic neoplasm.

Langerhans cell histiocytosis of thyroid and bilateral parotid diagnosed on fine needle aspiration cytology

“…The morphology of FDCS can vary widely, and thus it is reasonable to apply the relevant markers CD21, CD23, CD35, D240, and/or SSTR2a liberally when confronted with an epithelioid, syncytial, and/or spindle cell lesion with abundant admixed inflammatory cells. 27 In our case, characteristic morphology with the presence of both S-100 and CD1a positivity by ICC, the diagnosis of LCH was made. In addition to pathological features, clinically bilateral enlargement of parotid in young people can have many clinical differentials of inflammatory processes like sarcoidosis and mumps, which was also the scenario in our case.…”

“…However, compared to LCH and RDD, the quality of the non‐neoplastic infiltrate is less consistent and unfortunately less specific diagnostically. The morphology of FDCS can vary widely, and thus it is reasonable to apply the relevant markers CD21, CD23, CD35, D240, and/or SSTR2a liberally when confronted with an epithelioid, syncytial, and/or spindle cell lesion with abundant admixed inflammatory cells 27 . In our case, characteristic morphology with the presence of both S‐100 and CD1a positivity by ICC, the diagnosis of LCH was made.…”

Langerhans cell histiocytosis involving only the thymus in an adult: A case report

“…LCH is a rare proliferative disorder of the dendritic and reticulocyte systems, which belongs to the category of histiocytic neoplasms in hematological diseases, and is characterized by abnormal proliferation of cells of the monocyte–phagocyte system and tissue infiltration as the main pathological features[ 3 ]. Lesions can involve almost every system of the body.…”