A 6mm punch biopsy of normal appearing epidermis reveals stellar cells that contain intracytoplasmic granules having the shape of a tennis racquet. These cells demonstrate some myeloid surface markers and can interact closely with T lymphocytes. The cells described above are best referred to as which of the following?

Question

A 6mm punch biopsy of normal appearing epidermis reveals stellar cells that contain intracytoplasmic granules having the shape of a tennis racquet.  These cells demonstrate some myeloid surface markers and can interact closely with T lymphocytes.  The cells described above are best referred to as which of the following?

Quizplus · Accepted Answer

Langerhans cells (not to be confused with Langhans giant cells, a type of multinucleated cell formed from macrophages) are the form of dendritic cell most commonly found in the skin and mucous membranes. Dendritic cells are professional antigen presenting cells that interact closely with T lymphocytes. Dendritic are the most effective form of antigen presenting cell because they constitutively express MHC Class II and the co-stimulatory B7 cell surface molecules. They also take up antigen by constant endocytosis and pinocytosis from their environment. Langerhans cells are derived from the myeloid cell line and express myeloid cell surface markers. They contain characteristic "racquet-shaped" intracytoplasmic granules (Birbeck granules) that are only visible on electron microscopy. (Choice A) Kupffer cells are macrophage-derived cells present in the liver that compose part of the reticuloendothelial system. Kupffer cells lie within the hepatic sinusoids and, like any other macrophage, serve a phagocytic role in the liver. (Choice C) Merkel cells are neuroendocrine cells of the basal layer of the epidermis, often found in association with nerve projections, that play a role in perception of touch. They are associated with a rare but highly malignant form of skin cancer known as Merkel cell carcinoma. (Choice D) Melanocytes are pigment producing cells of the epidermis that arise from the neural crest cells and migrate to the basal layer of the epidermis during embryogenesis. They possess dendritic processes that intercalate between the remaining cells of the epidermis and facilitate the delivery of pigment-laden melanosomes from the melanocyte to the keratinocytes. (Choices E and F) Macrophages can be found in the skin, possess myeloid cell surface markers, and when stimulated, are able to produce dendrite-like extensions of their cytoplasm. Macrophages can also differentiate into multinucleated (Langhans) giant cells and epithelioid cells in the setting of granulomatous inflammation. However, monocytes and their derivatives do not produce Birbeck granules. Educational Objective: Langerhans cells are dendritic cells found in the skin that act as professional antigen presenting cells. These cells are derived from the myeloid cell line and they possess characteristic racquet-shaped intracytoplasmic granules known as Birbeck granules.

A 6mm Punch Biopsy of Normal Appearing Epidermis Reveals Stellar