A Case of Pulmonary Langerhans Cell Sarcoma Simultaneously Diagnosed with Cutaneous Langerhans Cell Histiocytosis Studied by Whole-Exome Sequencing

Langerhans cell histiocytosis developing acute lymphoblastic leukemia

The sequential occurrence of Langerhans cell histiocytosis and acute leukemia in only one individual has been reported previously; however, it is rarely observed that Langerhans cell histiocytosis can transform into acute lymphoblastic leukemia, and the underlying mechanisms remain unclear. In this report, we have analyzed a case of acute lymphoblastic leukemia converted from Langerhans cell histiocytosis using high-throughput sequencing method, and found that mitogen-activated protein kinase gene mutation, which can act as a marker for poor prognosis, might be involved in disease transformation. This is the first description about acute lymphoblastic leukemia B-cell type after Langerhans cell histiocytosis diagnosis and therapy in China.

Langerhans cell sarcoma involving skin and showing epidermotropism: A comprehensive review

Langerhans cell sarcoma (LCS) is rare and aggressive; patients have an overall survival rate of less than 50%. We present a 62-year-old man with a history of superficial spreading melanoma of the upper back with sentinel lymph node metastasis, Langerhans cell histiocytosis, and LCS. The patient presented with erythematous papules and scaly areas on his face, neck, arms, chest, abdomen, and legs. A skin biopsy revealed a proliferation of large neoplastic cells involving the dermis and with epidermotropism. These cells had atypical bean-shaped nuclei, with ample cytoplasm and abundant mitotic figures including atypical forms. Immunohistochemical studies showed the tumor to be diffusely positive for CD1a, S100 protein, and langerin (CD207) and negative for melanocytic markers. Some tumor cells were positive for cyclin D1. A diagnosis of LCS involving the skin was established. The present study is a very unusual case of LCS showing epidermotropism. The patient's history of metastatic melanoma posed additional challenges for diagnosis, underlying the need of immunophenotyping in these cases. Consensus for optimal standard therapy has not been established in LCS, and thus, early recognition is important since these neoplasms tend to recur and metastasize. LCS in skin is discussed and published cases are comprehensively reviewed.

A case of Langerhans cell sarcoma on the scalp: Whole-exome sequencing reveals a role of ultraviolet in the pathogenesis

Langerhans cell sarcoma (LCS) is a high-grade neoplasm with overtly malignant cytological features and a Langerhans cell phenotype. The underlying genetic features are poorly understood, and only a few alterations, such as those of the MARK pathway-related genes, CDKN2A and TP53 have been reported. Here we present a 70-year-old male with LCS on the scalp and pulmonary metastasis. The multinodular tumor, 3.0 cm in diameter, consisted of diffusely proliferated pleomorphic cells with numerous mitoses (53/10 HPFs). Immunohistochemically, the tumor cells were positive for CD1a, Langerin and PD-L1, and the Ki-67 labeling index was 50%. These pathological features were consistent with LCS, and were also observed in the metastatic tumor. Whole-exome sequencing revealed that both the primary and metastatic tumors harbored a large number of mutations (>20 mutations/megabase), with deletion of CDKN2A and TP53 mutation, and highlighted that the mutational signature was predominantly characteristic of ultraviolet (UV) exposure (W = 0.828). Our results suggest, for the first time, that DNA damage by UV could accumulate in Langerhans cells and play a role in the pathogenesis of LCS. The high mutational burden and PD-L1 expression in the tumor would provide a rationale for the use of immune checkpoint inhibitors for treatment of unresectable LCS.

Incidence, Clinical Features, and Outcomes of Langerhans Cell Sarcoma in the United States

BACKGROUND

Limited knowledge exists on the incidence, treatment patterns, and long-term outcomes of Langerhans cell sarcoma (LCS) in the United States.

PATIENTS AND METHODS

We performed a retrospective study of LCS patients diagnosed between 2001 and 2014 using the Surveillance, Epidemiology, and End Results (SEER) and National Cancer Data Base (NCDB) databases. Incidence was calculated from SEER, and treatment patterns and outcomes were calculated from NCDB.

RESULTS

A total of 25 and 52 cases of LCS were reported to SEER and NCDB, respectively. The overall incidence of the disease was 0.2 per 10,000,000 and did not differ by race (P = .56) or sex (P = .33). The median age at diagnosis was 62 (range, 19-90) years. Of the 52 patients from NCDB, 20 (39%) received chemotherapy as first-line therapy, 24 (46%) received surgery, and 15 (29%) received radiotherapy. The 1-year overall survival (OS) rate was 62%, and the median OS was 19 months. After censoring the patients with bone marrow and reticuloendothelial system involvement, no significant difference in OS was noted between the patients who were managed with or without surgery (P = .75). Postsurgical radiation or chemotherapy were not associated with improvement in median OS (P = .25). Patients who were managed with radiotherapy had a better OS compared to those who received no radiotherapy (P = .03).

CONCLUSION

This dual-national registry study shows that LCS is extremely rare and has a poor prognosis. Radiotherapy may offer a survival advantage to patients with locoregional disease without bone marrow and reticuloendothelial system involvement.