Histiocytosis - cutaneous manifestations of hematopoietic neoplasm and non-neoplastic histiocytic proliferations

Therapie des nekrobiotischen Xanthogranuloms - Fallserie und aktuelle Literatur: Therapy of necrobiotic xanthogranuloma - case series and review of the literature

Das nekrobiotische Xanthogranulom ist eine seltene Erkrankung, die zu den Nicht‐Langerhans‐Zell‐Histiozytosen gehört. Charakteristisch sind gelbliche Hautveränderungen, die typischerweise periorbital lokalisiert sind. Extrakutane Manifestationen aller Organe sind möglich und können potenziell lebensbedrohliche Komplikationen verursachen. Die Erkrankung gehört zu den fakultativen Paraneoplasien und zeigt eine hohe Assoziation zu Paraproteinämien. Diese Aspekte sollten in der Umfelddiagnostik berücksichtigt werden. Da die Erkrankung sehr selten ist, gibt es bislang keine standardisierten Richtlinien zur Therapie. Als erfolgreiche Therapieregime haben sich insbesondere die Kombination aus Prednisolon und Chlorambucil sowie die intravenösen Immunglobuline herausgestellt. Wir präsentieren vier Fälle aus unserer Klinik sowie die aktuellen Ergebnisse der Literatur in diesem Mini‐Review und möchten damit die therapeutische Herausforderung sowie die Relevanz der Erarbeitung von Richtlinien unterstreichen.

Therapy of necrobiotic xanthogranuloma - case series and review of the literature

Necrobiotic xanthogranuloma is a rare disease that is part of the non-Langerhans cell histiocytoses. It is characterized by yellowish skin lesions, which are typically periorbitally localized. Extracutaneous manifestations of all organs are possible and can cause potentially life-threatening complications. The disease also belongs to the facultative paraneoplasias and is often associated with paraproteinemia. These aspects should be considered regarding further diagnostics. Due to the rarity of the disease, there are no standardized guidelines for therapy so far. The combination of prednisolone and chlorambucil as well as intravenous immunoglobulins seem to be effective therapeutic options. We present four cases from our clinic as well as the current results of the literature in this mini-review and would like to highlight the therapeutic challenge as well as the need for the development of guidelines.

Necrobiotic Xanthogranuloma With Associated Monoclonal Gammopathy Presenting as an Eyelid Nodule

Necrobiotic xanthogranuloma (NXG) is a progressive non-Langerhans cell histiocytosis with a predilection for the periorbital area. NXG is most commonly associated with monoclonal gammopathy and ophthalmic complications. The authors present a 69-year-old man who was evaluated for a left upper eyelid nodule and plaques on the lower extremities, trunk, abdomen, and right upper extremity. Biopsy of the eyelid was supportive for NXG. Serum protein electrophoresis was positive for a monoclonal gammopathy, IgG light chain kappa. MRI showed preseptal involvement. The periocular nodules cleared with a high dose of prednisone; however, the other skin lesions persisted. Bone marrow biopsy showed kappa-restricted 6% plasma cells and he was treated with intravenous immunoglobulin. This case illustrates the importance of clinicopathologic correlations to render an NXG diagnosis.

Imaging features of juvenile xanthogranuloma

BACKGROUND

Juvenile xanthogranuloma is rare in children and there are limited data on its imaging features.

OBJECTIVE

To analyze the computed tomography (CT) and magnetic resonance imaging (MRI) features of juvenile xanthogranuloma in children.

MATERIALS AND METHODS

A retrospective review was performed of clinical and radiographic data of histologically confirmed juvenile xanthogranuloma between January 2009 and June 2020.

RESULTS

Fourteen children (4 girls, 10 boys; age range: 1 day to 13 years, mean age: 73 months) were included in the study: 4/14 had CT only, 5/14 had MRI only and 5/14 had CT and MRI. Sites of extracutaneous juvenile xanthogranuloma involvement included subcutaneous soft tissue (8/14), liver (2/14), lungs (2/14), kidney (2/14), nose (2/14), pancreas (1/14), central nervous system (1/14) and greater omentum (1/14), mainly manifested as single or multiple nodules or masses in different organs. On CT, the lesions mainly manifested as an iso-hypo density mass with mild or marked enhancement. On MRI, the lesions mainly manifested as slightly hyperintense on T1 and slightly hypointense on T2, with decreased diffusivity and homogeneous enhancement. Juvenile xanthogranuloma was not included in the imaging differential diagnosis in any case.

CONCLUSION

Juvenile xanthogranuloma mainly manifests as single or multiple nodules or masses in different organs. Slight hyperintensity on T1 and slight hypointensity on T2 with decreased diffusivity and homogeneous enhancement are relatively characteristic imaging findings of juvenile xanthogranuloma. Combined with its typical skin lesions and imaging features, radiologists should include juvenile xanthogranuloma in the differential diagnosis when confronted with similar cases.

What is the Role of Different Macrophage Subsets in the Evolution of Juvenile Xanthogranulomas?

There are several activated forms of macrophages: 2 main groups are designated M1 and M2. While M1 macrophages have proinflammatory, bactericidal, and phagocytic functions and are the dominant phenotype observed in the early stages of inflammation, M2 macrophages are involved in constructive processes such as tissue repair; they play a role in wound healing and are required for revascularization and re-epithelialization. Juvenile xanthogranuloma (JXG) is the most common non-Langerhans cell histiocytosis. Its pathogenesis is not well understood, but it is not considered a neoplastic entity. JXGs possibly appear as a reaction to a nonspecific injury such as trauma or viral infection, although a genetic predisposition has been suggested in some cases. Tissue damage leads to a histiocytic response. JXGs appear, evolve toward maturation, and then most of them spontaneously regress. Young JXGs are characterized by small macrophages scattered in the dermis, in apposition close to the epidermis. As the lesion matures, the number of foamy macrophages and Touton cells increases and other cell types such as plasma cells, lymphocytes, and polymorphs are observed. Regressing xanthogranulomas will show numerous spindle cells in Significant values are in bold.a storiform distribution, interstitial fibrosis, and few foamy and Touton cells. In this study, we studied the immunophenotypic profile of macrophages found in cutaneous JXGs according to their stage of maturation. We examined the skin biopsies from 25 patients; all were embedded in paraffin and stained with hematoxylin and eosin and for immunohistochemistry. Typically, all JXGs were positive for factor XIIIa and CD4, and were negative for CD1a. The following histiocyte markers were used: CD68, CD204, CD163, MAC387, and HAM56. Images were analyzed by Image J software; data were statistically evaluated by SAS 9.0 software. The cases showed a slight predominance of males and the preference of the JXGs for the axial skin. Lesions occupied the papillary and reticular dermis in 85% of the cases and extended to the subcutaneous fat in the remainder. Compared with mature and regressing JXGs, younger lesions had a higher density of M1 macrophages, stained with MAC387. This antibody labels the histiocytes that have recently arrived in the areas of inflammation. As the lesions matured, there was an overwhelming predominance of M2 macrophages. These cells tended to cluster against the epidermis, except in the 2 cases in phase of regression. This suggests that there is a cross-talk between the epidermis and macrophages and that receptors, cytokines, chemokines, and adhesion molecules may play a role in the development and evolution of JXGs. These results indicate that, for most of their life, JXGs are formed by repairing M2 macrophages and are not just an M1 macrophagic response to a local antigen. The process appears to be influenced by chemical-mediator epidermal-macrophage cross-talking, considering the tendency of these cells to accumulate against the dermoepidermal junction.

Oral Juvenile Xanthogranuloma: A Clinicopathological, Immunohistochemical and BRAF V600E Study of Five New Cases, with Literature Review

Juvenile xanthogranuloma (JXG) is the most common form of non-Langerhans cell histiocytosis and oral mucosal involvement is exceedingly rare. Histiocytic disorders harbor activating mutations in MAPK pathway, including the report of BRAF V600E in JXG of extracutaneous site. However, no information is available for oral JXG. Herein, the clinicopathological and immunohistochemical features of five new oral JXG were evaluated in conjunction with literature review. Also, we assessed the BRAF V600E in oral samples. Five oral JXG were retrieved from pathology archives. Morphological and immunohistochemical analyses were performed. The BRAF V600E status was determined with TaqMan allele-specific qPCR. The series comprised of three female and two male patients, most of them adults, with a median age of 39 years (range 13-68 years). Clinically, the lesions appeared as asymptomatic solitary nodules, measuring until 2.5 cm, with more incident to the buccal mucosa. Morphologically, most of the cases presented classical histological features of JXG, with histiocytic cells consistent with the non-Langerhans cell immunophenotype. BRAF V600E was not detected in the cases tested. This is the first and largest published series of oral JXG affecting adults and a Brazilian population. The molecular pathogenesis of oral JXG remains unknown. Clinicians and pathologists must recognize JXG to avoid misdiagnoses with oral benign or malignant lesions.

A Hematologic Disease Disguised as Cutaneous Candidiasis

Langerhans cell histiocytosis is a rare hematologic neoplasm with a myeloid origin, which can affect numerous organs, the skin being the second most frequently affected by this disease. In this report, a case of a 44-year-old female, who was intermittently followed due to a suspected persistent cutaneous candidiasis in which a skin biopsy revealed Langerhans cell histiocytosis with immunohistochemistry positive for CD1a and S100 protein, is described. The management of Langerhans cell histiocytosis is difficult because these disorders respond inconsistently to immunosuppressive and chemotherapeutic strategies. The authors present this case to highlight a differential diagnosis of refractory cutaneous candidiasis and raise awareness of the importance of skin biopsy in these cases.

The triptych of mixed histiocytosis: a systematic review of 105 cases and proposed clinical classification

Histiocytoses are one of the ultimate diagnostic challenges that every physician face at least once in his/her life. Giving their protean manifestation and differentiated therapeutic needs, histiocytosis requires extensive characterization and multidisciplinary management. Mixed histiocytosis is an emerging group of syndromes defined by the overlap of Langerhans cell histiocytosis and another histiocytic disorder of different type. Despite rare, it may account for up to a fifth of systemic histiocytosis patients in some series. In this work, we comprehensively review for the first time the clinical, radiological, histopathological and molecular features of mixed histiocytosis in children and adults. Moreover, we propose a clinical classification in three groups that differentiate patients with systemic involvement and worse overall survival to other groups with more localized manifestations and indolent behavior, wanting to ease their recognition and treatment. Interestingly we also found that mixed histiocytosis harbor BRAFV600E mutations with a higher frequency comparing to all other histiocytoses, and may therefore benefit of specific inhibitory drugs.

Juvenile Xanthogranuloma: An Entity With a Wide Clinical Spectrum

Juvenile xanthogranulomas (JXGs) are rare, benign lesions that belong to the large group of non-Langerhans cell histiocytoses. JXG presents with 1 or more erythematous or yellowish nodules that are usually located on the head or neck. Most JXG lesions are congenital or appear during the first year of life. Extracutaneous involvement is rare, but the literature traditionally suggests investigating the possibility of ocular compromise. JXG is mainly a clinical diagnosis, but a skin biopsy may sometimes be needed for confirmation. JXGs on the skin are self-limiting and usually do not require treatment. This review describes the clinical and therapeutic aspects of JXG, emphasizing available evidence and the diagnosis of extracutaneous involvement.

Emperipolesis and S100 expression may be seen in cutaneous xanthogranulomas: A multi-institutional observation

Cutaneous Rosai-Dorfman disease (RDD) can be difficult to distinguish from other non-Langerhans cell histiocytoses, particularly xanthogranuloma (XG). Pathologists use S100 immunoreactivity, abundant plasma cells, and the presence of emperipolesis to distinguish RDD from XG. However, S100 expression has been reported in XG and, in practice, we have occasionally observed emperipolesis in cases that were otherwise clinically and pathologically consistent with XG. We present 10 cases of XG with emperipolesis and variable S100 immunoreactivity. Histologically, 7 cases were most in keeping with XG, and a histologic differential of XG versus RDD was raised in the remaining 3 cases. All 10 cases were clinically consistent with XG. Notably, none of these cases showed abundant plasma cells. Nine cases showed variable S100 immunostaining, ranging from focal/weak expression, to focal/strong, diffuse/moderate, and diffuse/strong expression. Histiocytes in all cases were CD68 positive and CD1a negative. We conclude that emperipolesis and S100 expression in a skin biopsy cannot reliably distinguish XG from cutaneous manifestations of RDD. Clinical correlations are essential, as are histologic clues to a diagnosis of classic XG that include an abundance of foamy mononuclear cells, Touton giant cells, and an absence of pale-stained histiocytes, abundant plasma cells, fibrosis, or vascular proliferation.