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HS. (A) Syncytial sheets of markedly atypical cells with eosinophilic cytoplasm, prominent nucleoli, and mitotic activity (H&E stain, 400× magnification); (B) diffuse CD163 reactivity (immunohistochemistry, 400× magnification); (C) separate case showing sheets of tumor cells with marked nuclear pleomorphism, foamy cytoplasm, and scattered admixed non-neoplastic inflammatory cells (H&E stain, 400× magnification). The morphology of histiocytic sarcoma is not specific and would be compatible with other pleomorphic tumors given a different immunoprofile. Thus, diagnosis of HS requires a broad panel of immunohistochemical stains to exclude other tumors. HS, histiocytic sarcoma.
Source publication
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 n...
Context in source publication
Context 1
... last tumor in the intrinsic histiocytic and dendritic cell category we will consider is HS. By definition this lesion expresses multiple histiocytic markers and consists of cytologically malignant cells (Figure 4), while requiring exclusion of other more specific diagnostic entities, a task which is quite challenging pathologically and important clinically, given the extensive list of diverse lesions we have already discussed (17). Although an extremely rare diagnosis, HS is still a heterogeneous category, and likely encompasses distinct tumor types with overlapping morphology and immunophenotype. ...
Citations
... Its clinical manifestations include pain, splenomegaly, fever, cough, polyhydramnios, headache, protruding eyes, enlarged lymph nodes, unstable walking, and even neuropsychiatric symptoms. It has a low incidence and can be seen in any age group, mostly in children, but in adults, it is most insidious, often with a chronic course, and the specific treatment is not yet validated [2]. In this case report, we present an adult patient with a highly suspicious thymoma of anterior superior mediastinum, with a postoperative pathological diagnosis of LCH involving only the thymus. ...
Background:
Langerhans cell histiocytosis (LCH) is a rare disease of unknown etiology. LCH involving the thymus is mainly seen in pediatric patients and is extremely rare in adults. In this report, we describe a rare case of LCH originating from the thymus in an adult.
Case summary:
A 56-year-old man was admitted in April 2022 with complaints of intermittent dizziness since 2020, which had worsened in the previous 10 d. The physical chest examination was negative, and there was a history of hypertension for > 2 years. Chest computed tomography showed a nodular soft tissue density shadow in the anterior mediastinum measuring approximately 13 mm × 9 mm × 8 mm. Postoperative pathological findings confirmed the diagnosis of LCH.
Conclusion:
It is challenging to differentiate LCH involving the thymus from thymoma in imaging features. Pathological biopsy remains the gold standard when an anterior mediastinal occupying lesion is found.
LCH has a distinct site predilection and cytological feature. However, it can cause diagnostic difficulties at unusual sites or deviated cytomorphology. FNAC is a minimally invasive procedure that can be performed in any organ (parotid and thyroid where biopsy is not commonly indicated) and multiple sites/organs simultaneously for diagnosis. FNA sampling can also help with cell block preparation for performing immunohistochemistry and molecular studies if necessary.
