p53 Is a Helpful Marker in Distinguishing Langerhans Cell Histiocytosis From Langerhans Cell Hyperplasia

Langerhans Cell Hyperplasia Mimicking Langerhans Cell Histiocytosis: A Rare Complication of COVID-19 Vaccination

Langerhans cell histiocytosis (LCH) is a rare disorder characterized by the abnormal proliferation of Langerhans cells, a type of immune cell that is normally present in the skin and various other tissues. LCH can affect people of any age but is most commonly diagnosed in children. We report a case of a patient with LCH who developed ipsilateral axillary lymphadenopathology post-COVID-19 vaccination. Lymph node biopsy showed diffuse Langerhans cell hyperplasia which mimicked LCH. Clinically and radiologically, it looked to be a reactive lymph node. The patient was kept on follow up only and after 1 year of follow up the size of lymph nodes regressed confirming to be reactive in nature rather than neoplastic. To the best of our knowledge, this is the second case of Langerhans cell hyperplasia post-COVID-19 vaccination being reported in the literature.

Thyroid Langerhans cell histiocytosis concurrent with papillary thyroid carcinoma: A case report and literature review

Langerhans cell histiocytosis (LCH) is a clonal neoplasm of myeloid dendritic cells, rarely involving the thyroid gland. Papillary thyroid carcinoma (PTC) is the most common histological subtype of thyroid cancer. We report a rare case of a 34-year-old Chinese woman who has LCH with PTC and cervical lymph node metastasis of LCH, with a review of the literature. The patient has thyroid nodules and cervical lymph node enlargement detected by neck ultrasound during physical examination. Fine needle aspiration cytology (FNAC) showed PTC with Hashimoto's thyroiditis and BRAF V600E mutation after thyroidectomy and lymph node dissection. Histopathological examination suggests that LCH was concurrent with classical PTC, accompanied by LCH cervical lymph node metastasis. No BRAF, HRAS, and TERT promoter mutations were detected in LCH metastatic lesions. The patient is in stable clinical condition currently.

Langerhans cell histiocytosis in adults: literature review

Langerhans cells histiocytosis is a variant of malignant histiocytosis. The course and symptoms vary. patients with localized forms have a better prognosis, because local therapy is effective. patients with multifocal forms of histiocytosis receive systemic drug therapy, which cures some of the patients. This review provides up-to-date data about typical presentation of the organ involvement, diagnosis, course and therapy of various forms of Langerhans cells histiocytosis.

mRNA sequencing analysis and growth inhibitory effects of palbociclib on cell lines from canine histiocytic proliferative disorders

Canine histiocytic proliferative disorders include aggressive and fatal diseases, such as histiocytic sarcoma (HS) and histiocytosis (SyH). The molecular mechanisms underlying cell proliferation need to be elucidated for the development of effective treatments. In the present study, mRNA expression levels were comprehensively analysed in cell lines derived from localized HS, disseminated HS, SyH and Langerhans cell histiocytosis (LCH) in dogs. Based on the results obtained, the growth inhibitory effects of palbociclib, a CDK4/6 inhibitor, were verified with the cell lines in vitro and in xenograft mouse model. Hierarchical clustering and principal component analysis plots of mRNA expression profiles divided the cell lines into three groups: a localized HS group, disseminated HS/SyH group, and LCH. The results of an ingenuity pathway analysis suggested that the MAPK signalling pathway was activated in the localized HS and LCH cell lines, and the PI3K signalling pathway in the disseminated and localized HS cell lines. In all cell lines, the expression of the tumour suppressor genes TP53, CDKN2A and CDKN1A was down-regulated, whereas that of Rb was preserved. In vitro assessments revealed the growth inhibitory effects of palbociclib in all cell lines examined. In a xenograft mouse model using a cell line from disseminated HS, palbociclib exerted significant growth inhibitory effects. These results suggest the potential of palbociclib as a therapeutic drug candidate for the treatment of malignant histiocytic proliferative disorders of the dog.

Cutaneous Pseudolymphoma With Langerhans Cell Hyperplasia-A Rare Case With Clinical Presentation Mimicking Malignancy and Potential Diagnostic Pitfall

ABSTRACT

We describe a rare case of cutaneous pseudolymphoma with Langerhans cell hyperplasia. An 84-year-old female patient presented with erythematous and pernicious-looking plaques on her scalp that had been present for months. Histologically, lymphoid follicles consisting of mixed-type lymphocytes and Langerhans cells were aggregated focally. The diagnosis was verified by several immunohistochemical stains and by clinical evaluation. Skin lesions were steadily resolved with low-dose corticosteroid and hydroxychloroquine.

Localized Acral Sclerosing Langerhans Cell Histiocytosis: A New Form of Presentation of Cutaneous Langerhans Cell Histiocytosis

Langerhans cell histiocytosis (LCH) is a rare proliferative disorder, more frequent in children, characterized by an abnormal accumulation of Langerhans cells admixed with eosinophils, lymphocytes, neutrophils, and macrophages. The clinical presentation is variable and depends on whether a single or multiple organs are affected. Skin lesions are common in LCH (40% of cases) and represent a frequent form of presentation (in up to 80% of cases). Cutaneous manifestations of LCH are highly variable, frequently presenting as crusted papules or scaly seborrheic-like lesions localized in the scalp. We report the first case of a localized acral sclerosing LCH, a new form of LCH. This case highlights the broad and surprising form of presentation of LCH which may be overlooked and can significantly delay its diagnosis. The development of systemic disease may occur months to years after the initial skin presentation. Prompt diagnosis and treatment may prevent progression to systemic disease, as documented in some cases.