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.

Even though a plethora of systemic therapies have been proposed for necrobiotic xanthogranuloma (NXG), there is no systematic review on this topic in literature.
To review all existing literature on the systemic therapy of NXG in order to identify the most effective therapies.
All reported papers in the literature were screened for systemic treatments of NXG. Papers without proper description of the therapies, papers describing topical therapy, and articles without assessment of effectiveness were excluded. Subsequently, we analyzed 79 papers and a total of 175 cases.
The most effective treatments for NXG are intravenous immunoglobulins (IVIG), corticosteroids, and combination therapies including corticosteroids.
Corticosteroids and IVIG should therefore be considered first-line treatments in patients with NXG.

Necrobiotic xanthogranuloma is a rare type of non-Langerhans histiocytosis, whose main clinical features are the development of red-brown, purplish or yellowish skin papules and nodules, which evolve by forming infiltrated plaques. The periorbital region is the most commonly affected site. Some cases have lesions on the torso or extremities, with no facial involvement. Extracutaneous involvement of the ocular, respiratory, and cardiac tissues have also been described. Most patients have an associated monoclonal gammopathy (IgG k and λ). The treatment is difficult, with progression and recurrence. We present the clinical case of a 65-year-old woman, who was hospitalized for multiple erythematous plaques and placards, with fine squames and telangiectasis on the surface, disseminated within the scalp, ears, trunk, lower limbs; some plaques have a circinate border with reddish-purple, slightly protruding edges and a whitish and erosive atrophic center. The lesions within the scalp are alopecic. The disease began 15 years ago, the patient being diagnosed with Psoriasis vulgaris and treated with dermatocorticoids and Cignolin, with no remarkable results. Paraclinical investigations did not reveal any associated pathologies. Histopathological and immunohistochemical examination confirmed the diagnosis of necrobiotic Xanthogranuloma. The patient was treated with antihistamines, Neuromultivit, Vit E 100mg/day, Oximed spray, Atoderm emollient cream, Neopreol ointment, with slow favorable evolution. The physical examination and laboratory investigations for the diagnosis and surveillance of malignant diseases should be performed on a regular basis in patients with NXG. Our patient had lesions with a course of 15 years, with no development of multiple myeloma or other systemic involvement.

Necrobiotic xanthogranuloma (NXG) is a non-Langerhans cell histiocytosis classically associated with paraproteinemia attributable to plasma-cell dyscrasias or lymphoproliferative disorders. Despite the morbidity of NXG, the literature is limited to case reports and small studies, and diagnostic criteria are lacking.
To evaluate the characteristics of NXG and propose diagnostic criteria.
This multicenter cross-sectional study was conducted at tertiary academic referral centers and followed by a systematic review and a consensus exercise. The multicenter cohort included patients with NXG diagnosed at the Brigham and Women\'s and Massachusetts General Hospitals (2000-2018), the University of Iowa Hospitals and Clinics (2000-2018), and the University of Pennsylvania Health System (2008-2018). The systematic review was conducted in 2018 and included patients with NXG identified in the Cochrane, Ovid EMBASE, PubMed, and Web of Science databases. The consensus exercise was conducted by 8 board-certified dermatologists to identify diagnostic criteria.
Demographic factors, comorbidities, clinical features, and treatment response.
Of 235 included patients with NXG (34 from the multicenter cohort and 201 from the systematic review results), the mean (SD) age at presentation was 61.6 (14.2) years; 147 (62.6%) were female. Paraproteinemia was detected in 193 patients (82.1%), most often IgG-κ (117 patients [50.0%]). A malignant condition was detected in 59 patients (25.1%), most often multiple myeloma (33 patients [14.0%]). The overall rate of paraproteinemia and/or a malignant condition was 83.8% (197 patients). In the multicenter cohort, evolution of paraproteinemia into multiple myeloma was observed up to 5.7 years (median [range], 2.4 [0.1-5.7] years) after NXG presentation. Cutaneous lesions consisted of papules, plaques, and/or nodules, typically yellow or orange in color (113 of 187 [60.4%]) with a periorbital distribution (130 of 219 [59.3%]). The eye was the leading site of extracutaneous involvement (34 of 235 [14.5%]). In the multicenter cohort, intravenous immunoglobulin had the best treatment response rate (9 of 9 patients [100%]), followed by antimalarial drugs (4 of 5 patients [80%]), intralesional triamcinolone (6 of 8 patients [75%]), surgery (3 of 4 patients [75%]), chemotherapy (8 of 12 patients [67%]), and lenalidomide or thalidomide (5 of 8 patients [63%]). The consensus exercise yielded 2 major criteria, which were (1) clinical and (2) histopathological features consistent with NXG, and 2 minor criteria, consisting of (1) paraproteinemia, plasma-cell dyscrasia, and/or other associated lymphoproliferative disorder and (2) periorbital distribution of cutaneous lesions. In the absence of foreign body, infection, or another identifiable cause, fulfillment of both major and at least 1 minor criterion were proposed to establish the diagnosis of NXG.
Necrobiotic xanthogranuloma is a multisystem disorder associated with paraproteinemia and malignant conditions. The proposed diagnostic criteria may advance clinical research and should be validated.

Histiocytoses, including Langerhans cell histiocytosis (LCH), juvenile or adult xanthogranuloma (AXG) and Rosai-Dorfman disease (RDD), are rare disorders characterized by the proliferation of cells derived from monocyte/macrophage lineages. A few cases of LCH coexisting with xanthogranuloma or RDD have been reported. The etiology of these diseases remains unclear. However, oncogenic BRAFV 600E mutations have been identified in LCH. Here, we report the case of a 26-year-old Japanese man with a 3-month history of a solitary occipital nodule. No abnormality was detected in his other organs, and a total resection of the nodule was performed. Histopathological examination revealed the coexistence of LCH and AXG with prominent emperipolesis characteristic of RDD. Immunohistochemistry showed that most of the large histiocytes were positive for CD68, weakly positive or negative for S100, and negative for CD207 and CD1a, supporting the diagnosis of AXG. The tumor cells with emperipolesis did not show S100-positive findings characteristic of RDD. The focally aggregated oval histiocytic cells were positive for CD1a, CD207, CD68 and S100, and were compatible with the immunophenotype of LCH cells. In addition, these cells were positive for BRAFV 600E mutation. The tumor cells in our patient exhibited a cellular morphology characteristic of multiple histiocytoses in a solitary cutaneous nodule, which may imply an etiological association among LCH, AXG and RDD. To our knowledge, this is the first report of a BRAFV 600E mutation-positive case of LCH coexisting with AXG. Because patients with BRAFV 600E mutation have higher risks of multisystemic LCH and recurrence, we should carefully follow up the patient.

Necrobiotic xanthogranuloma (NXG) is an uncommon non-Langerhans cell histiocytosis involving skin and extracutaneous tissues. The lesions are usually asymptomatic and commonly appear in the periorbital area. Paraproteinemia is closely associated with NXG and its pathogenesis remains unclear. NXG prognosis is poor with several treatments showing variable results. Treatment of monoclonal gammopathy with alkylating agents does not necessarily influence the activity of the skin disease and vice versa. The aim of this systematic review is to summarize all reported treatments of necrobiotic xanthogranuloma of the skin, with or without underlying malignant condition and based on articles from the PubMed database using the query \'necrobiotic xanthogranuloma treatment\', both in English and German, about \'human\' subjects and published between 1980 and 2014, documenting adequate treatment for NXG. Mainly individual case reports, small case series and retrospective studies were found. Treatment options include topical and systemic corticosteroids, thalidomide, high-dose intravenous immunoglobulin (IVIG), chlorambucil, cyclophosphamide, fludarabine, rituximab, melphalan, infliximab, interferon alpha, cladribine, hydroxychloroquine, azathioprine, methotrexate, laser therapy, radiotherapy, surgery, PUVA, plasmapheresis and extracorporeal photopheresis. Randomized controlled trials and studies on long-term outcomes after treatment were not found and are necessary to focus on in the future.

The xanthodermatoses consist of a heterogeneous group of cutaneous disorders characterized by the macroscopic yellow hue seen on examination. This hue is attributable to the chemical structure of the accumulating substances within the skin or surrounding tissues. The most common culprits are lipids (cholesterol and triglycerides), elastin, and bilirubin. Exogenous sources of yellow pigment include yellow dyes (including hennas) and metal salts. This article will focus on recognition of these entities, classified in terms of morphology and the site of initial eruption, in order to support the recognition and diagnosis of these widely variable conditions.

Adult orbital xanthogranulomatous diseases are rare entities and encompass a group of disorders with varying manifestations that are poorly understood. Taken as a group, there are non-Langerhans histiocytic disorders (type II) that are diagnosed histologically by the presence of foamy histiocytes, Touton giant cells, and varying degrees of fibrosis. Based on the accompanying systemic associations, there are 4 main categories of adult xanthogranulomatous disease: adult-onset xanthogranuloma, adult-onset asthma and periocular xanthogranuloma, necrobiotic xanthogranuloma, and Erdheim-Chester disease. Herein, we discuss the etiopathogenesis, systemic associations, methods of diagnosis, and treatment options for these disorders.

Necrobiotic xanthogranuloma (NXG) was first described in 1980 by Kossard and Winkelmann in an article in which they discussed 8 patients with xanthomatous plaques who were noted to have monoclonal gammopathy, predominantly of the Ig(immunoglobulin)G-κ type.(1) Since then more than 50 patients with this disorder have been described, with approximately 80% of them having an associated monoclonal gammopathy. We describe the first case, to our knowledge, of NXG with associated monoclonal gammopathy treated with thalidomide plus dexamethasone, achieving complete resolution of the skin lesions and sustaining response more than 3 years after treatment.

Monoclonal gammopathy may manifest itself through a range of skin disorders, including plane normolipemic xanthoma and necrobiotic xanthogranuloma. The present paper describes two patients with these cutaneous symptoms. The first has extensive areas of skin affected by flat xanthomas, monoclonal gammopathy with > 10% infiltration of bone marrow with clonal plasmocytes and, according to PET-CT, unclear lymphadenopathy in the retroperitoneal area. The size of this lymphadenopathy (histologically no malignant infiltration and no confirmed infectious aetiology) has not changed significantly over a 4-year follow-up. Repeated PET-CT scans showed decrease in SUV value in this infiltration from 7.5 to 3.8. Four cycles of treatment with a combination of bortezomib, cyclophosphamide and dexamethasone brought neither reduction in monoclonal immunoglobulin nor change to skin morphology. We believe that the abdominal lymphadenopathy is associated with xanthomatosis but have been unable to confirm this unequivocally. The second patient is being followed up for more than 10 years, originally for MGUS, later for asymptomatic multiple myeloma. Last year, painful subcutaneous and cutaneous infiltrates, isolated on an upper limb and more frequent on lower limb, started to occur. These infiltrates are palpable. PET-CT imaging provided an excellent depiction of these infiltrates, showing no pathology on the head, chest and abdomen and no osteolytic foci on the skeleton. CT imaging showed clearly numerous infiltrates in the skin and subcutaneous tissue of lower limbs, particularly both shanks, reaching up to 2 cm in depth. The largest infiltrate, measuring 3.5 by 2 by 10 cm, was identified in the distal dorsal part of the right shank. PET imaging of lower limbs showed distinctly pathological accumulation in all infiltrates described above; the accumulation of glucose in the lower part of the right shank reached 10.0 SUV. CT images of lower limbs showed increased density saturated hypodermis even in the areas where there is no increased accumulation of 18 fluoroglucose. Following 40 Gy irradiation, the size of infiltrate in the radiated area decreased and their soreness ceased.
CONCLUSIONS: PET-CT imaging offered information on extra-cutaneous signs of plane normolipemic xanthomas and provided excellent depiction of the areas of the skin and hypodermis affected by necrobiotic xanthogranuloma. Chemotherapy with cyclophosphamide, bortezomib and dexamethasone brought no reduction in monoclonal immunoglobulin concentration, and no reduction in plane normolipemic xanthomas. Radiotherapy targeted at large foci of xanthogranulomas led to partial regression and ceased infiltrate soreness.