~Ihe nature of Langerhans cells is disputed. ~fhey have been considered effete melanocytes (1, 2), postmelanin-synthetic cells (3), melanocyte precursors (4), intraepidermal nerve endings (5, 6), or postdivisional stages of previously melanogenic melanocytes (7). Under the electron microscope, melanocytes and Langerhans cells are distinguished by highly characteristic cytoplasmic or-ganelles: m...

A morphometric analysis of tumoral Langerhans cells and activated macrophages was conducted using canine cutaneous tumors (65 cases of canine cutaneous histiocytoma and 7 cases of pyogranuloma). The histiocytic origin of the tumor cells was confirmed using immunohistochemistry. The parameters of the morphometric analysis included cellular and nuclear size and shape and the nuclear:cytoplasmic r...

Langerhans cell histiocytosis is a disease which results from accumulation or proliferation of a clonal population of cells with the phenotype of Langerhans cells arrested at an early stage of activation that are functionally defi cient. The etiology and pathogenesis of the disorder are still unknown. There are ongoing investigations to determine whether it is a reactive or a neoplastic disease...

BACKGROUND Langerhans cell histiocytosis is a rare proliferative histiocytic disease of unknown etiology. Histologically, it is characterized by granuloma-like proliferation of Langerhans-type dendritic cells derived from bone marrow. Many investigators have suggested the possible role of viruses such as Epstein-Barr virus, human herpesvirus-6 (HHV-6), herpes simplex virus (HSV) types 1 and 2, ...

Langerhans cell histiocytosis (LCH) is a clonal disorder believed to be derivedfrom cells of the dendritic system. Fascin, a 55-kd actin-bundling protein, represents a highly selective marker for dendritic cells of lymphoid tissues and peripheral blood and is involved in the formation of dendritic processes in maturing epidermal Langerhans cells. Since lesional cells of LCH may represent Langer...

Exposure to ultraviolet-B radiation impairs cellular immune responses. This immunosuppression seems to be associated with Langerhans cell migration. DNA damage appears to play a key role because enhanced nucleotide excision repair, a pathway essential for elimination of ultraviolet-B-induced DNA lesions, strongly counteracts immunosuppression. To determine the effect of DNA repair on ultraviole...

We describe a 2 ½ year old boy presenting with fever, abdominal pain and splinter haemorrhages of the nails. On further examination there were signs of pneumonia with pleural effusion. This was treated with mini-thoracotomy, drainage and intravenous antibiotics. Further diagnostic workup for underlying causes showed diffuse cystic lung disease, suggestive of Langerhans cell histiocytosis. This ...

Objective. To present a case of otic Langerhans' cell histiocytosis in an adult. Also included the diagnosis and management of the condition and a review of the relevant literature. Case Report. We report a case of a 41-year-old man with a history of persistent unilateral ear discharge associated with an aural polyp. Radiological imaging showed bony lesions of the skull and a soft-tissue mass w...

Recent data from murine models have confirmed that Langerhans cells are not the only population of APCs in the skin involved in initiating immune responses. In healthy human skin, we identify CD1a(+) dermal APCs located close to the lymphatic vessels in the upper layers of the dermis that are unequivocally distinct from migrating Langerhans cells but exhibit both potent allostimulatory capacity...

Accepted 29 March 1996 In 1953, Lichtenstein introduced the unifying term 'histiocytosis X' to embrace several previous eponyms, including eosinophilic granuloma, Letterer-Siwe disease and Hand-Schuller-Christian disease.' In 1987, a more prominent designation, Langerhans cell histiocytosis (LCH), was recommended to replace histiocytosis X.' The term is more appropriate as it reflects the fact ...