title: Indeterminate cell tumor: a rare dendritic neoplasm.
abstract: Indeterminate cell tumor (ICT) is a rare neoplastic dendritic cell disorder that has been poorly defined due to its rarity and poorly understood histogenesis and pathogenesis. It is characterized by a proliferation of dendritic cells, which mimic Langerhans cells immunophenotypically (positive for CD1a and S-100 protein), but lack Birbeck granules characteristic of Langerhans cells. The clinical, morphologic, immunophenotypic, and ultrastructural features of 5 ICT cases are reported in an attempt to further define ICT and to examine the postulated relationship between indeterminate cells and Langerhans cells. Four of 5 patients were females, and 4 of 5 were older than 68 years. Three of 5 patients had cutaneous lesions, whereas 2 presented with cervical lymph node involvement. Two patients had a possible association with lymphoma: first patient had a history of progressive follicular lymphoma that led to patient's demise and the second patient had unexplained systemic lymphadenopathy and died 1 week after the biopsy. All 5 ICT cases expressed CD1a and S-100 protein, but lacked Langerin expression and Birbeck granules ultrastructurally. Interestingly, a t(14;18) was detected by fluorescence in situ hybridization in the ICT cells of the patient with previous follicular lymphoma and a monoclonal kappa light chain gene rearrangement was detected by polymerase chain reaction in the patient with systemic lymphadenopathy. In both cases, there was no morphologic or immunophenotypic evidence of a concurrent B-cell lymphoma. In conclusion, ICT is a rare neoplasm that can occur de novo or in association with a B-cell lymphoma, possibly as a result of B-cell dedifferentiation caused by relatively unknown mechanisms. Finally, Langerin immunostaining may be used as a surrogate marker for the ultrastructural demonstration of Birbeck granules, the absence of which represents a strong diagnostic criterion for ICT.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of California Irvine (UCI), Irvine, CA, USA.
authors.forename: Sherif A
authors.initials: SA
authors.lastname: Rezk
authors.forename: Dominic V
authors.initials: DV
authors.lastname: Spagnolo
authors.forename: Russell K
authors.initials: RK
authors.lastname: Brynes
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Weiss
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D018949:Antigens, CD1 / Q000378:metabolism; D003713:Dendritic Cells / Q000378:metabolism / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D015322:Gene Rearrangement, B-Lymphocyte; D019337:Hematologic Neoplasms / Q000150:complications / Q000235:genetics / Q000473:pathology*; D006646:Histiocytosis, Langerhans-Cell / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D037181:Lectins, C-Type / Q000378:metabolism; D016393:Lymphoma, B-Cell / Q000150:complications; D008297:Male; D037241:Mannose-Binding Lectins / Q000378:metabolism; D016133:Polymerase Chain Reaction; D009418:S100 Proteins / Q000378:metabolism
chemical_list: D015703:Antigens, CD; D018949:Antigens, CD1; C419393:CD1a antigen; C121916:CD207 protein, human; D037181:Lectins, C-Type; D037241:Mannose-Binding Lectins; D009418:S100 Proteins