Role of p16 in the pathogenesis of Langerhans cell histiocytosis

Rosai-Dorfman Disease Displays a Unique Monocyte-Macrophage Phenotype Characterized by Expression of OCT2

Rosai-Dorfman disease (RDD) is a rare histiocytosis with heterogenous clinical features. In this study, we characterized the histologic and phenotypic features in 33 RDD patients to better define the pathologic diagnosis. Cases included 24 patients with extracutaneous disease ("R" group), and 9 patients with lesions limited to the skin or subcutaneous tissue ("C" group). We identified OCT2 as a novel marker for the monocyte-macrophage phenotype of RDD, expressed in 97% of RDD cases. In contrast, OCT2 expression was seen in 0% of Erdheim-Chester disease cases and 6.7% of Langerhans cell histiocytosis cases. Other markers useful in the diagnosis of RDD included S100 (100%), CD163 (88%), and cyclin D1 (97%). In a subset of cases, RDD showed moderate to strong expression of factor 13a (30%), p16 (64%), and phosphorylated extracellular signal-regulated kinase (45%); RDD was uniformly negative for ZBTB46, CD1a, and langerin. Within the "R group" of RDD, increased expression of factor 13a or phosphorylated extracellular signal-regulated kinase showed a statistically significant association with multifocal disease (P<0.05). Identification of the unique monocyte-macrophage phenotype of RDD with OCT2 expression furthers our understanding of this complex disease and allows for more uniform classification.

Cervical langerhans cell histiocytosis mimicking cervical tuberculosis: A Case report

RATIONALE

Langerhans cell histiocytosis (LCH) involving adult cervical vertebrae is relatively rare clinically.

PATIENT CONCERNS

An 18-year-old male patient exhibited a 1-month history of neck pain, restricted neck mobility, and numbness and weakness of both upper limbs. The patient reported no pain at other sites, exhibited no fever or night sweats, and was unable to recall any recent injury.

DIAGNOSES

On the basis of the radiological features of the lesion and laboratory tests, there was a high possibility that the patient had a tuberculosis lesion. Postoperative GeneXpert and Mycobacterium tuberculosis (MTB) culture results showed MTB negative. Postoperative pathological results showed: (Cervical 4 vertebrae) LCH.

INTERVENTIONS

Our department did an anterior approach operation. The patient was treated with prednisone combined with vincristine after operation.

OUTCOMES

The patient was discharged from the hospital with complete remission of cervical pain and rapid relief of neurological symptoms.

LESSONS

Computed tomography-guided biopsy of lesion tissue must be performed when a suspected infection occurs in young patients. If possible, the lesion tissue obtained during the operation should be cultured and pathologically examined for early diagnosis.

Immunohistochemical evaluation of p16 expression in cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions

BACKGROUND

Expression of p16 is frequently evaluated in melanocytic lesions. Expression of p16 in cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions has not been well characterized.

METHODS

We evaluated p16 expression in a cohort of histiocytic (reticulohistiocytoma, Langerhans cell histiocytosis, xanthogranuloma, Rosai Dorfman disease and xanthoma), fibrohistiocytic (dermatofibroma, epithelioid fibrous histiocytoma and dermatofibrosarcoma protuberans) and undifferentiated (atypical fibroxanthoma and pleomorphic undifferentiated sarcoma) lesions. A group of melanocytic lesions (Spitz nevus, ordinary nevus, spitzoid melanoma and non-spitzoid melanoma) were also evaluated as reference. Each case was scored by the proportion of p16-positive cells and by staining intensity.

RESULTS

Immunoreactivity for p16 was found in almost all histiocytic (28/30, 93%) and fibrohistiocytic (22/24, 92%) lesions. About half of the undifferentiated lesions also exhibited p16 staining (9/17, 53%). Most of the melanocytic cases examined in this study expressed p16. A wide range of staining intensity and proportion of p16-positive cells was observed in most groups.

CONCLUSION

Expression of p16 is common, albeit variable in proportion and intensity, amongst a wide variety of cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions. Further studies are required to determine if p16 expression is useful in distinguishing benign from malignant neoplasms of these types.

The presence of CXCR4+ CD1a+ cells at onset of Langerhans cell histiocytosis is associated with a less favorable outcome

PURPOSE

Langerhans Cell Histiocytosis (LCH) is a neoplastic disorder characterized by tissue accumulating CD1a⁺ histiocytes which frequently carry somatic mutations. Irrespective of mutation status, these LCH-cells display constitutively active kinases belonging to the MAPK pathway. We evaluated, in retrospect, the contribution of individual components of the MAPK-activating and chemotaxis-promoting TNF-CXCR4-CXCL12 axis to LCH manifestation and outcome.

EXPERIMENTAL DESIGN

CXCR4, CXCL12 and TNF protein expression was immunohistochemically analyzed in 70 LCH-affected biopsies. The presence of CXCR4⁺CD1a⁺ cells in peripheral blood (PB) and/or bone marrow (BM) samples was evaluated by flowcytometry in 13 therapy-naive LCH-patients.

RESULTS

CXCL12 was detected in 68/70 (97%) biopsies. CXCR4⁺LCH-cells were present in 50/70 (71%) biopsies; their presence was associated with higher levels of intralesional TNF. Circulating CD1a⁺CXCR4⁺ cells were detected in 4/13 (31%) therapy-naïve LCH-patients which displayed BRAF^V600E (2/4), MAP2K1 (1/4) or no (1/4) mutations in their tissues. These CD11c co-expressing CD1a⁺CXCR4⁺cells migrated to CXCL12 in chemotaxis assays. Lesional CXCR4⁺LCH-cells were detected in 18/20 cases who presented with LCH manifestation at multiple sites and in 5/23 (22%) patients who developed additional lesions after initially presenting with a single lesion. The CXCR4 status at onset proved to be an independent risk factor for LCH reactivation in multivariate analysis (odds ratio 10.4, p = 0.034).

CONCLUSIONS

This study provides the first evidence that CXCR4 is involved in the homing and retention of LCH-cells in CXCL12-expressing tissues and qualifies CXCR4 as a candidate prognostic marker for less favorable disease outcome.

Prognostic significance of gelsolin and MMP12 in Langerhans cell histiocytosis

Background

Gelsolin and matrix metalloproteinase 12 (MMP12) expression has been reported in Langerhans cell histiocytosis (LCH), but the clinical significance of this expression is unknown. We investigated the associations of these proteins with clinical manifestations in patients diagnosed with LCH.

Methods

We performed a retrospective analysis of clinical data from patients diagnosed with LCH and followed up between 1998 and 2008. Available formalin-fixed, paraffin-embedded specimens were used for gelsolin and MMP12 immunohistochemical staining. We analyzed the expression levels of these proteins and their associations with LCH clinical features.

Results

Specimens from 36 patients (20 males, 16 females) with a diagnosis of LCH based on CD1a positivity with clinical manifestations were available for immunohistochemical staining. Median patient age was 62 months (range, 5 to 207). The expression of gelsolin varied; it was high in 17 patients (47.2%), low in 11 patients (30.6%), and absent in 8 patients (22.2%). The high gelsolin expression group had a higher tendency for multi-organ and risk organ involvement, although the trend was not statistically significant. MMP12 was detected only in 7 patients (19.4%) who showed multi-system involvement (P=0.018) and lower event-free survival (P=0.002) in comparison to patients with negative MMP12 staining.

Conclusion

Gelsolin and MMP12 expression may be associated with the clinical course of LCH, and MMP12 expression may be particularly associated with severe LCH. Further studies of larger populations are needed to define the precise role and significance of gelsolin and MMP12 in the pathogenesis of LCH.