Histopathology 2014, 65, 742–748. DOI: 10.1111/his.12481
Bone marrow involvement of Langerhans cell histiocytosis: immunohistochemical evaluation of bone marrow for CD1a, Langerin, and S100 expression Hyun-Ki Kim, Chan-Jeoung Park, Seongsoo Jang, Young-Uk Cho, Sang Hyuk Park,1 Kyung Nam Koh,2 Ho Joon Im2 & Jong Jin Seo2 Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, 1 Department of Laboratory Medicine, Pusan National University School of Medicine, Pusan National University Hospital, Busan, and 2Department of and Pediatrics, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea Date of submission 28 May 2014 Accepted for publication 14 June 2014 Published online Article Accepted 3 July 2014
Kim H-K, Park C-J, Jang S, Cho Y-U, Park S H, Koh K N, Im H J & Seo J J (2014) Histopathology 65, 742–748
Bone marrow involvement of Langerhans cell histiocytosis: immunohistochemical evaluation of bone marrow for CD1a, Langerin, and S100 expression Aims: Although bone marrow (BM) involvement in Langerhans cell histiocytosis (LCH) is a negative prognostic indicator, there are no widely accepted criteria to define BM involvement in LCH. We evaluated the BM of LCH patients at diagnosis by immunohistochemical (IHC) staining for S100, CD1a and Langerin, along with other features. Methods and results: We retrospectively reviewed the records of 75 patients diagnosed as LCH at our center. IHC stains of Langerin, CD1a and S100 were done using paraffin-embedded tissue sections. Only three cases showed massive involvement of clustered Langerhans cells. There were linear associations between positive cell count and disease extent. Some
discordant results between Langerin and CD1a IHC stains were noted. Among cases showing positive results for all three IHC stains, six patients (54.5%) were in the multisystem group, and three patients (27.3%) had cytopenias. The reactivation-free survival rates did not differ between the group positive for CD1a or Langerin, and the group negative for Langerin and CD1a. Conclusions: Langerin and CD1a seem to be useful markers of Langerhans cells, and S100 might be a nonspecific marker for these cells, in the BM. Both Langerin and CD1a IHC staining is needed to evaluate the BM involvement of LCH.
Keywords: bone marrow, immunohistochemical stain, Langerhans cell histiocytosis, Langerin
Introduction Langerhans cell histiocytosis (LCH) is defined by the WHO classification system as a clonal neoplastic proliferation of Langerhans-type cells that express CD1a, Langerin and S100 protein, and that shows Birbeck Address for correspondence: C-J Park, Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 138-736, Korea. e-mail: [email protected] © 2014 John Wiley & Sons Ltd.
granules by ultrastructural examination.1 LCH is a rare disease of unknown aetiology, with very heterogeneous clinical presentation, ranging from a singlesystem involvement, which is usually benign, to a multisystem life-threatening disease.2 The prominent inflammatory component and occasional benign clinical course of LCH suggested that it might not be a neoplasm. Nonetheless, the discovery of frequently recurring oncogenic BRAF mutations in this disease, along with rare KRAS and TP53 mutations, now supports its classification as a neoplasm.3
Langerin, CD1a and S100 IHC in BM of LCH
Notwithstanding advances in the understanding of LCH, there have been few reports about bone marrow (BM) features in LCH patients.4–6 The frequency of Langerhans cells in BM varies considerably between studies. Galluzzo et al.4 have reported Langerhans cells in 14% of multisystem LCH patients with riskorgan involvement at diagnosis, which was confirmed by CD1a immunohistochemical (IHC) staining after biopsy. Nonetheless, Minkov et al.5 reported immunocytochemical evidence of CD1a-positive cells in 46% of 33 multisystem LCH samples and 18% of 24 single system LCH samples. This discrepancy might arise from differences in the methods of detection and evaluation. Given that BM involvement of the LCH seems to be a negative prognostic indicator, BM samples from LCH patients should be assessed accurately.6–10 Nonetheless, there are no widely accepted criteria for defining BM involvement in LCH.5 Some markers have been used to identify Langerhans cells. CD1a is a specific marker for LCH, and in practical terms, the detection of CD1a-positive Langerhans cells remains the gold standard for LCH diagnosis.11 S100 has traditionally been also used to distinguish LCH from other processes.12 Recent studies suggest that Langerin expression seems to be a highly sensitive and relatively specific to LCH.13,14 Although CD1a, S100 and Langerin have been widely evaluated for markers of LCH at the primary site of disease, they have not been evaluated together as markers of BM involvement. Therefore, we here evaluated BM of LCH patients at diagnosis with S100, CD1a and Langerin IHC stains, and analyzed the clinical features and other BM findings for our patient series.
Materials and methods We analyzed BM samples of patients who presented at the Asan Medical Center with histopathologically confirmed LCH from 1997 to 2012. Seventy-five patients had paraffin-embedded bone marrow biopsy specimens, at the time of their diagnosis, available for additional IHC staining. Bilateral aspirates and trephine biopsies were obtained in 68 patients, and unilateral aspirates and trephine biopsies in seven patients. Clinical information was assessed through a retrospective chart review. Cases were classified into four categories according to the extent of disease at the time of diagnosis.2 Single-system (SS) LCH was defined as involvement of one organ without organ dysfunction. SS LCH was subdivided into single site (unifocal bone, skin or lymph node involvement; © 2014 John Wiley & Sons Ltd, Histopathology, 65, 742–748.
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SS-SS) and multiple site (SS-MS) cases. Multisystem (MS) LCH was defined as the involvement of two or more organs with or without organ dysfunction. MS LCH was subdivided into a low-risk (MS-low) and risk group (MS-risk). The risk group was defined by the involvement of one or more risk organs (liver, lungs, spleen or hematopoietic system). Liver involvement was defined as liver enlargement (>3.0 cm below the costal margin, proven by sonography) and/or liver dysfunction (hyperbilirubinemia, hypoproteinemia, hypoalbuminemia, elevated transaminases, ascites, and edema) and/or biopsy proven involvement. Spleen involvement was defined as spleen enlargement (>2 cm below the costal margin, proven by sonography). Clinical involvement of the hematopoietic system was defined as the presence of mono-, bi- or pancytopenia (haemoglobin < 9.0 g/dl in infants or
Bone marrow involvement of Langerhans cell histiocytosis: immunohistochemical evaluation of bone marrow for CD1a, Langerin, and S100 expression Hyun-Ki Kim, Chan-Jeoung Park, Seongsoo Jang, Young-Uk Cho, Sang Hyuk Park,1 Kyung Nam Koh,2 Ho Joon Im2 & Jong Jin Seo2 Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, 1 Department of Laboratory Medicine, Pusan National University School of Medicine, Pusan National University Hospital, Busan, and 2Department of and Pediatrics, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea Date of submission 28 May 2014 Accepted for publication 14 June 2014 Published online Article Accepted 3 July 2014
Kim H-K, Park C-J, Jang S, Cho Y-U, Park S H, Koh K N, Im H J & Seo J J (2014) Histopathology 65, 742–748
Bone marrow involvement of Langerhans cell histiocytosis: immunohistochemical evaluation of bone marrow for CD1a, Langerin, and S100 expression Aims: Although bone marrow (BM) involvement in Langerhans cell histiocytosis (LCH) is a negative prognostic indicator, there are no widely accepted criteria to define BM involvement in LCH. We evaluated the BM of LCH patients at diagnosis by immunohistochemical (IHC) staining for S100, CD1a and Langerin, along with other features. Methods and results: We retrospectively reviewed the records of 75 patients diagnosed as LCH at our center. IHC stains of Langerin, CD1a and S100 were done using paraffin-embedded tissue sections. Only three cases showed massive involvement of clustered Langerhans cells. There were linear associations between positive cell count and disease extent. Some
discordant results between Langerin and CD1a IHC stains were noted. Among cases showing positive results for all three IHC stains, six patients (54.5%) were in the multisystem group, and three patients (27.3%) had cytopenias. The reactivation-free survival rates did not differ between the group positive for CD1a or Langerin, and the group negative for Langerin and CD1a. Conclusions: Langerin and CD1a seem to be useful markers of Langerhans cells, and S100 might be a nonspecific marker for these cells, in the BM. Both Langerin and CD1a IHC staining is needed to evaluate the BM involvement of LCH.
Keywords: bone marrow, immunohistochemical stain, Langerhans cell histiocytosis, Langerin
Introduction Langerhans cell histiocytosis (LCH) is defined by the WHO classification system as a clonal neoplastic proliferation of Langerhans-type cells that express CD1a, Langerin and S100 protein, and that shows Birbeck Address for correspondence: C-J Park, Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 138-736, Korea. e-mail: [email protected] © 2014 John Wiley & Sons Ltd.
granules by ultrastructural examination.1 LCH is a rare disease of unknown aetiology, with very heterogeneous clinical presentation, ranging from a singlesystem involvement, which is usually benign, to a multisystem life-threatening disease.2 The prominent inflammatory component and occasional benign clinical course of LCH suggested that it might not be a neoplasm. Nonetheless, the discovery of frequently recurring oncogenic BRAF mutations in this disease, along with rare KRAS and TP53 mutations, now supports its classification as a neoplasm.3
Langerin, CD1a and S100 IHC in BM of LCH
Notwithstanding advances in the understanding of LCH, there have been few reports about bone marrow (BM) features in LCH patients.4–6 The frequency of Langerhans cells in BM varies considerably between studies. Galluzzo et al.4 have reported Langerhans cells in 14% of multisystem LCH patients with riskorgan involvement at diagnosis, which was confirmed by CD1a immunohistochemical (IHC) staining after biopsy. Nonetheless, Minkov et al.5 reported immunocytochemical evidence of CD1a-positive cells in 46% of 33 multisystem LCH samples and 18% of 24 single system LCH samples. This discrepancy might arise from differences in the methods of detection and evaluation. Given that BM involvement of the LCH seems to be a negative prognostic indicator, BM samples from LCH patients should be assessed accurately.6–10 Nonetheless, there are no widely accepted criteria for defining BM involvement in LCH.5 Some markers have been used to identify Langerhans cells. CD1a is a specific marker for LCH, and in practical terms, the detection of CD1a-positive Langerhans cells remains the gold standard for LCH diagnosis.11 S100 has traditionally been also used to distinguish LCH from other processes.12 Recent studies suggest that Langerin expression seems to be a highly sensitive and relatively specific to LCH.13,14 Although CD1a, S100 and Langerin have been widely evaluated for markers of LCH at the primary site of disease, they have not been evaluated together as markers of BM involvement. Therefore, we here evaluated BM of LCH patients at diagnosis with S100, CD1a and Langerin IHC stains, and analyzed the clinical features and other BM findings for our patient series.
Materials and methods We analyzed BM samples of patients who presented at the Asan Medical Center with histopathologically confirmed LCH from 1997 to 2012. Seventy-five patients had paraffin-embedded bone marrow biopsy specimens, at the time of their diagnosis, available for additional IHC staining. Bilateral aspirates and trephine biopsies were obtained in 68 patients, and unilateral aspirates and trephine biopsies in seven patients. Clinical information was assessed through a retrospective chart review. Cases were classified into four categories according to the extent of disease at the time of diagnosis.2 Single-system (SS) LCH was defined as involvement of one organ without organ dysfunction. SS LCH was subdivided into single site (unifocal bone, skin or lymph node involvement; © 2014 John Wiley & Sons Ltd, Histopathology, 65, 742–748.
743
SS-SS) and multiple site (SS-MS) cases. Multisystem (MS) LCH was defined as the involvement of two or more organs with or without organ dysfunction. MS LCH was subdivided into a low-risk (MS-low) and risk group (MS-risk). The risk group was defined by the involvement of one or more risk organs (liver, lungs, spleen or hematopoietic system). Liver involvement was defined as liver enlargement (>3.0 cm below the costal margin, proven by sonography) and/or liver dysfunction (hyperbilirubinemia, hypoproteinemia, hypoalbuminemia, elevated transaminases, ascites, and edema) and/or biopsy proven involvement. Spleen involvement was defined as spleen enlargement (>2 cm below the costal margin, proven by sonography). Clinical involvement of the hematopoietic system was defined as the presence of mono-, bi- or pancytopenia (haemoglobin < 9.0 g/dl in infants or
