Indeterminate cell tumor: a rare dendritic neoplasm

• Published in: The American journal of surgical pathology Vol. 32; no. 12; p. 1868
• Main Authors: Rezk, Sherif A, Spagnolo, Dominic V, Brynes, Russell K, Weiss, Lawrence M
• Format: Journal Article
• Language: English
• Published: United States 01.12.2008
• Subjects: Antigens, CD - metabolism; Antigens, CD1 - metabolism; Dendritic Cells - metabolism; Dendritic Cells - pathology; Diagnosis, Differential; Female; Gene Rearrangement, B-Lymphocyte; Hematologic Neoplasms - complications; Hematologic Neoplasms - genetics; Hematologic Neoplasms - pathology; Histiocytosis, Langerhans-Cell - pathology; Humans; Immunohistochemistry; In Situ Hybridization, Fluorescence; Lectins, C-Type - metabolism; Lymphoma, B-Cell - complications; Male; Mannose-Binding Lectins - metabolism; Polymerase Chain Reaction; S100 Proteins - metabolism
• ISSN: 1532-0979
• DOI: 10.1097/PAS.0b013e31818593d6

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.