Multiple eruptive cephalic histiocytomas in a case of T-cell lymphoma. A xanthomatous stage of benign cephalic histiocytosis in an adult patient?

Benign cephalic histiocytosis: case report and review of the literature

Benign cephalic histiocytosis (BCH) is a rare type of non-Langerhans histiocytic disorder, usually presenting with small, yellow-red or yellow-brown, asymptomatic papules, located mostly on the head and neck of infants and young children. The histopathologic hallmark of BCH is a well-circumscribed histiocytic infiltrate in the superficial to mid-reticular dermis. BCH is a self-healing disorder, with the eruptions regressing spontaneously in most cases; therefore no treatment is required. We present a case of BCH in a 7-month-old boy who was referred to our department with multiple, asymptomatic, yellow-red papules located on his face, and we review 55 cases published in the English-language literature in an effort to better describe and understand this unusual entity.

Monocytes promote tumor cell survival in T-cell lymphoproliferative disorders and are impaired in their ability to differentiate into mature dendritic cells

A variety of nonmalignant cells present in the tumor microenvironment promotes tumorigenesis by stimulating tumor cell growth and metastasis or suppressing host immunity. The role of such stromal cells in T-cell lymphoproliferative disorders is incompletely understood. Monocyte-derived cells (MDCs), including professional antigen-presenting cells such as dendritic cells (DCs), play a central role in T-cell biology. Here, we provide evidence that monocytes promote the survival of malignant T cells and demonstrate that MDCs are abundant within the tumor microenvironment of T cell-derived lymphomas. Malignant T cells were observed to remain viable during in vitro culture with autologous monocytes, but cell death was significantly increased after monocyte depletion. Furthermore, monocytes prevent the induction of cell death in T-cell lymphoma lines in response to either serum starvation or doxorubicin, and promote the engraftment of these cells in nonobese diabetic/severe combined immunodeficient mice. Monocytes are actively recruited to the tumor microenvironment by CCL5 (RANTES), where their differentiation into mature DCs is impaired by tumor-derived interleukin-10. Collectively, the data presented demonstrate a previously undescribed role for monocytes in T-cell lymphoproliferative disorders.

Benign cephalic histiocytosis progressing into juvenile xanthogranuloma: a non-Langerhans cell histiocytosis transforming under the influence of a virus?

Benign cephalic histiocytosis (BCH) is best understood as a form of non-Langerhans cell histiocytosis, specifically as an early mononuclear variant of juvenile xanthogranuloma (JXG). However, the progression of BCH into JXG in the same patient has only been reported once before. We describe the case of a 2-year-old girl with asymptomatic, large, ill-defined infiltrated flat plaques over both cheeks, in addition to isolated papules. A punch biopsy of a plaque revealed dermal infiltration by vacuolated and scalloped histiocytes positive for CD68 KP-1, and that lacked expression of CD1a and S-100 protein, favoring macrophages over Langerhans cells. Electron microscopy study showed comma-shaped intracytoplasmic bodies in the histiocytic cells leading to the diagnosis of BCH. One year later, after an episode of varicella-zoster infection, the flat plaques over the cheeks became large reddish-yellow nodules, and in a second biopsy appeared to progress to JXG. Virus-related mechanisms of progression are discussed.