The bone marrow in urticaria pigmentosa and systemic mastocytosis. Cell composition and mast cell density in relation to urinary excretion of tele-methylimidazoleacetic acid

The bone marrow sections from five normal subjects and 18 patients with mastocytosis were examined to establish criteria to distinguish urticaria pigmentosa from systemic mastocytosis. Nine patients had increased numbers of mast cells in bone marrow sections stained with a long toluidine blue staining technique specific for mast cells, whereas five patients exhibited increased numbers of mast cells on May-Grünwald-Giemsa-stained smears of bone marrow. A positive correlation between the number of mast cells in sections of the bone marrow and the urinary excretion of the main histamine metabolite tele-methylimidazoleacetic acid was found. In ten of the examined bone marrow specimens, focal lesions containing mast cells, lymphocytes, and eosinophils appeared. The presence of these focal lesions together with either an increased number of mast cells in bone marrow sections and/or increased urinary excretion of telemethylimidazoleacetic acid is considered diagnostic of systemic mastocytosis. No patient exhibited myeloproliferative condition or other major hematologic abnormality.     

Treatment of urticaria pigmentosa using interferon alpha

Long-term treatment with interferon alpha (IFN-α) has recently been shown to reduce the bone marrow infiltrate and cutaneous lesions in systemic mast cell disease. We therefore administered this cytokine to six patients with urticaria pigmentosa for up to 12 months, using subcutaneous injections of 5×10⁶U, initially five times, and subsequently three times a week. The generally well-tolerated therapy resulted in marked improvement of the cutaneous symptoms, especially in three of the patients who suffered from very severe pruritus. Two of the patients with bone marrow infiltration showed normal findings after treatment. However, in none of the patients was there any change in the skin lesions, or decrease in the degree of cutaneous mast cell infiltration, as evidenced by light and electron microscopic examination. These findings indicate that IFN-α is highly effective in the control of symptoms, but otherwise does not influence the cutaneous lesions of urticaria pigmentosa.     

Expression of stem cell factor in cutaneous mastocytosis

Stem cell factor has recently been identified as a potent growth factor for bone marrow stem cells, melanocytes and mast cells. In order to evaluate its possible role in human mastocytosis, skin lesions from 13 patients with urticaria pigmentosa and five patients with mastocytomas, and normal skin specimens from five healthy donors were studied by immunohistochemistry, using polyclonal and monoclonal (hkl-12) antibodies against stem cell factor, and a monoclonal antibody (YB5.B8) against its receptor, the c-kit proto-oncogene product. Stem cell factor expression was noted in all sections studied, with an equal distribution pattern for both antibodies, but a weaker intensity with the hkl-12 reagent. Cytoplasmic staining was noted in keratinocytes, Langerhans cells, sweat gland ductal lining cells, mast cells, endothelial cells and spindle-shaped dermal stromal cells. An intense, diffusely granular reaction pattern was noted in all cells, except for a sparse, coarsely granular pattern in mast cells and stromal cells. In urticaria pigmentosa, staining was weaker in keratinocytes, but more prominent in Langerhans cells. In all sections, toluidine blue-positive mast cells and TA 99-positive basal epidermal melanocytes were the only cells to react with the c-kit antibody. Mastocytomas and urticaria pigmentosa lesions thus exhibit different patterns of stem cell factor expression. However, a possible pathogenetic role of this factor in mastocytosis remains to be determined.     

Urticaria pigmentosa--an obligate systemic disease? Results of nuclear medicine studies and etiopathogenetic significance

The objective of the present investigation was to establish the frequency of systemic spreading of urticaria pigmentosa by means of bone and bone marrow scintigraphy as a noninvasive imaging technique with a low radiation exposure. Bone scintigraphy: Seven of nine patients investigated showed diffuse and focal nuclide accumulation. After exclusion of other causes by reference to the case history and the clinical and chemical laboratory findings, these nuclide accumulations were regarded as mastocytosis-specific in accordance with the atypical localization. Bone-marrow scintigraphy: All the patient investigated showed a peripheral expansion of the bone marrow. This must be interpreted as an expansion of the macrophages of the bone marrow on the basis of the method used. Since the mast cell is regarded as a more highly differentiated form of the same cell-type as macrophages/monocytes, on the basis of the scintigraphic results presented, urticaria pigmentosa can be regarded pathogenetically as a hyperplasia of the macrophages of the bone marrow organ, with increased differentiation in mast cells. The extent of this differentiation and its pathological quality then determine the clinical signs and symptoms (cutaneous, systemic, or malignant mastocytosis). Urticaria pigmentosa thus has the character of a systemic disease.     

Urticaria pigmentosa. Systemic evaluation and successful treatment with topical steroids

Nine patients with adult-onset urticaria pigmentosa were studied for the incidence of extracutaneous mast cell involvement and the efficacy of potent topical corticosteroid therapy for cutaneous lesions. Seven of the nine patients had increased mast cells in the marrow biopsy specimens, and five patients had focal aggregates of mast cells. The bone scan was abnormal in one patient. Liver-spleen scans revealed a shift of colloid uptake from liver to spleen in four patients. No abnormal gastrointestinal tract roentgenograms were obtained. Urinary histamine metabolites correlated with nodular bone marrow involvement, but not with other parameters. Results of the psychoneurologic testing revealed significant deviation from the norm with a verbal memory deficit in all nine patients and abnormalities on the Minnesota Multiphasic Personality Inventory in four patients. All nine patients were treated with 0.05% betamethasone dipropionate ointment under occlusion over half of the body nightly for 6 weeks. Seven of nine patients treated responded with almost complete resolution of their lesions. Hypothalamic pituitary adrenal axis suppression was evaluated with intramuscular cosyntropin stimulation and metyrapone administration during treatment. Only two patients, both of whom used the medication improperly, developed transient abnormalities. Slow return of lesions was noted 6 months after completion of therapy. Remissions could be lengthened with single weekly applications of topical steroids. Systemic involvement is frequent in patients with cutaneous mast cell disease and it is best demonstrated by bone marrow biopsy. Mast cell lesions can be safely and effectively treated with topical steroids in motivated patients.     

Systemic mastocytosis

Systemic mastocytosis associated with urticaria pigmentosa seems to be strikingly more common than previously assumed. The diagnosis can be established by the investigation of bone marrow sections, whereas bone marrow smears are less reliable. Some mediators are produced by the enhanced number of mast cells; telemethyl imidazole acetic acid is the most suitable mediator to calculate the size of the mast cell pool. Investigations like this might offer an alternative to the examination of bone marrow sections in future.     

The cosmetic treatment of urticaria pigmentosa with Nd:YAG laser at 532 nanometers

Background Urticaria pigmentosa is a cutaneous disorder involving infiltration of the skin with mast cells. Histologically the papillary dermis has an increased number of mast cells with an increase in basal layer pigmentation. In addition to possible systemic symptoms, patients with urticaria pigmentosa can suffer emotionally from the cosmetic nature of this skin disease. Objective The purpose was to investigate the use of a diode‐pumped Nd:YAG laser at 532 nm for the treatment of the cosmetic comorbidity of urticaria pigmentosa lesions. Methods A 19‐year‐old white male with urticaria pigmentosa had multiple lesions on the dorsum of the hands and forearms. A test site on the right inner arm was treated with a DioLite? 532 nanometer laser. Because of satisfaction with the treatment of the test site lesions, multiple lesions on the dorsal hands and forearms were also treated with the DioLite? 532 nanometer laser. Results There was a dramatic clinical reduction in the amount of lesions on the dorsum of the hands and forearms. The test site lesions on the right inner arm had not recurred. Conclusion The diode‐pumped Nd:YAG laser at 532 nanometers should be considered part of a dermatologist's armamentarium for the treatment of a patient's cosmetic concerns with lesions of cutaneous mastocytosis.     

Macrophage subsets in different types of urticaria

Summary Biopsy specimens from lesional and uninvolved skin of nine patients with delayed pressure urticaria, three patients with acute urticaria, six patients with chronic recurrent urticaria, and four patients with urticaria pigmentosa were analyzed by routine histology and by immunochemistry for their reactivity with monoclonal antibodies to three different subsets of macrophages. Skin from 12 healthy volunteers served as control. Uninvolved skin of patients did not differ from that of healthy volunteers. An antibody against activated macrophages (27E10) was reactive to a marked extent with macrophages in wheals of pressure urticaria, more variably in acute and chronic urticaria, and practically not at all in urticaria pigmentosa. Antibodies with specificities for macrophages in healing (RM3/1) and normal (25F9) tissue reacted more markedly in all but pressure urticaria lesions, compared with normal skin. These findings indicate an active involvement of inflammatory macrophages in whealing reactions while these cells play apparently no role in cutaneous mast cell proliferation (urticaria pigmentosa).     

Ultrastructural findings in tissue mast cells in urticaria pigmentosa

In a study on 10 patients suffering from urticaria pigmentosa, biopsies of skin lesions were electron microscopically investigated. In contrast to normal skin, the mast cells showed irregular, partly bilobed nuclei, prominent nucleoli, hypogranulation, and rather small granules; giant granules were rarely observed. In addition, we frequently found degranulation, and the development of microvilli was much more prominent than with normal mast cells. These deviations from normal skin represent at least in part functional alterations. However, some of the findings suggest that urticaria pigmentosa may be considered a neoplastic disease of the tissue mast cells, although clear evidence is still lacking. In any case, our findings show that mast cells in mastocytosis are not identical with those in normal skin.     

Two novel mast cell phenotypic markers, monoclonal antibodies Ki-MC1 and Ki-M1P, identify distinct mast cell subtypes

Summary In order to identify more specific or selective mast cell markers, the reactivity of two monoclonal antibodies, Ki-MC1 and Ki-M1P, was studied by immunohistochemistry in two human cell lines (mast cell line HMC-1, basophilic cell line KU812), in mast cells cultured from blood precursors, in adherent mononuclear cells from peripheral blood, and in mast cells of tissue sections from 1 3 urticaria pigmentosa lesions, live mastocytomas and live normal skin specimens. Toluidine blue staining, fluorescence staining with FITC-conjugated avidin, and immunohistochemical staining (APAAP) with other mast cell reactive monoclonal antibodies, was performed for comparison. Double staining with the APAAP method, using the Ki-antibodies and toluidine blue, was also carried out. Both Ki-antibodies showed reactivity for skin mast cells, but with a different staining pattern. In addition, the Ki-MC1 antibody did not react with the cell lines, and reacted only with a few peripheral blood mononuclear cells and cultured mast cells. In contrast, the Ki-M1P antibody reacted with almost all cultured mast cells and blood mononuclear cells, but stained only about one-half of lesional and one-fifth of normal skin mast cells. Ki-M1P also reacted with many toluidine blue-negative dermal cells, particularly in urticaria pigmentosa. Ki-MC1 antibody can thus be considered as a useful additional marker for normal skin mast cells. In contrast, the Ki-M1 P antibody primarily identifies immature mast cells and monocytes/macrophages, suggesting that these cell types probably originate from the same bone marrow precursor.     

Mast cells with bilobed or multilobed nuclei in a nodular lesion of a patient with urticaria pigmentosa

Mast cells with bilobed or multilobed nuclei have only rarely been observed in the bone marrow of patients with systemic mastocytosis and in a case of subdural mast cell sarcoma. To our knowledge, they have not been reported in cutaneous mast cell disease. We report a rare occurrence of mast cells with bilobed or multilobed nuclei (atypical mast cell type II) in a nodular lesion of a 24-year-old woman with urticaria pigmentosa. The typical and atypical mast cells were confirmed by Giemsa and Leder's naphthol-AS-D-chloroacetate esterase stains and by immunohistochemical staining for tryptase and KIT protein (CD117). Although the nodular lesion with atypical mast cells did not appear to be cytologically malignant, the occurrence of atypical mast cells in a nodular lesion but not in a papular lesion might denote progression of the disease as suggested by the emergence of cells positive for p53.     

Cutaneous mastocytosis: demographic aspects and clinical features of 55 patients

BACKGROUND: Mastocytosis is a rare, heterogeneous group of disorder with abnormal increase of mast cells in one or more organ systems. OBJECTIVE: To evaluate the demographic and clinical features of cutaneous mastocytosis (CM). METHODS: Records of 55 patients with cutaneous mastocytosis were retrospectively analysed. RESULTS: Of the 22 females and 33 males, 80% had urticaria pigmentosa/maculopapular CM and 20% had mastocytoma. Of all cases, 81.8% had first lesions in childhood. The most common presentation was involvement of trunk together with extremities. Thirteen (23.6%) patients had history of bulla; Darier's sign was positive in 34 of 38 patients. Itching was the most common complaint, provocated by hot weather/bath. CONCLUSION: Clinical presentations of urticaria pigmentosa/maculopapular CM and mastocytoma are similar regarding gender, age of onset, age of diagnosis, and presence of Darier's sign and history of bulla. In contrast to mastocytoma, urticaria pigmentosa/maculopapular CM lesions were frequently located on trunk together with extremities.     

Photochemotherapy (PUVA) in the treatment of urticaria pigmentosa

Eight patients received PUVA for mastocytosis. Five women had typical adult-onset urticaria pigmentosa, without evidence of systemic disease. Another woman had suspected hepatic involvement while the remaining female had early-onset familial urticaria pigmentosa with morphologically atypical mast cells. The only male patient had cirrhosis with hepatic deposits of mast cells in addition to polycythaemia rubra vera. In all patients, except the man with systemic disease, there was reduced pruritus and wealing and partial to almost complete fading of the macules. The manifestations of urticaria pigmentosa recurred after treatment was discontinued. In both lesional and uninvolved skin there was no significant change in either the mean mast cell counts or mast cell ultrastructure after an average of twenty-seven PUVA exposures. In addition, PUVA did not cause a significant alteration in the histamine content of the skin. The beneficial effect of PUVA in urticaria pigmentosa therefore does not appear to be directly related to a change in mast cell numbers or morphology, or to the histamine concentration in the skin. Urticaria pigmentosa usually presents as a generalized maculo-papular rash which urticates on rubbing (Darier's sign). Many patients are troubled only by the unsightliness of the rash while some complain of pruritus, wealing or flushing. These symptoms are attributed to the release of histamine by mast cells which characteristically occur in increased numbers in the dermis. Symptomatic treatment is often unrewarding, but favourable results have been claimed for cimetidine with or without Hi blockers (Hirschowitz & Groarke, 1979; O'Laughlin & Bredfeldt, 1980) and for oral disodium cromoglycate (Soter, Austen & Wasserman, 1979; Czarnetski & Behrendt, 1981). In 1978, Christophers and colleagues reported that photochemotherapy (PUVA) produced symptomatic relief in all of ten adult patients with typical urticaria pigmentosa. Similarly encouraging results were subsequently reported from other centres (Ortonne et al., 1980; Allevato, Donatti & Cordero, 1980; Granerus, Roupe & Swanbeck, 1981; Väätäinen, Hannuksela & Karvonen, 1981). In this study we examined the effects of PUVA in eight adult patients with urticaria pigmentosa. Although PUVA produced a moderately good clinical response in seven out of these eight patients (reduced pruritus, reduced wealing and faded macules) quantitative studies failed to reveal a consistent effect of PUVA on either the mast cell population density or the histamine concentration in both lesional and clinically uninvolved skin. The findings arc discussed in relation to existing information concerning the effect of ultraviolet radiation (U VR) on mast cells and other constituents of the skin.     

Perivascular mast cells in urticaria pigmentosa

We have quantified perivascular mast cells in cases of urticaria pigmentosa, urticaria, and dermal hypersensitivity reactions. To facilitate reproducibility, the mast cells were counted for a precisely defined vessel unit. These vessel units were divided arbitrarily into those ≤55μm and > 55μm in largest diameters. Urticaria pigmentosa showed an average of 6.4 ± 1.9 and 22.8 ± 13.2 masts cells for vessel unit ≤ 55μm and ≤ 55μm, respectively. Urticaria yielded a lower number of mast cells: 1.5 ± 0.2 and 2.9 ± 0.9 for the same respective vessel units. Dermal hypersensitivity reactions revealed an average of 1.6 ± 0.4 and 2.2 ± 0.7 mast cells, and the normal skin showed 1.5 ± 0.3 and 2.4 ± 0.6 mast cells for each of the vessel units of ≤ 55μm and > 55μm. The perivascular mast cell distributions of urticaria pigmentosa are statistically different from those of urticaria and dermal hypersensitivity reactions with p < 0.0001. No statistical difference was noted between urticaria, dermal hypersensitivity reactions, and normal skin. The percentages of vessel units ≤ 55μm with ≥ 5 mast cells and vessel units < 55μm with ≥ 10 mast cells were determined for each case. The average percentage of vessel units for the former and latter in urticaria pigmentosa was 82.6% and 58.9%, respectively. Urticaria yielded 0% and 0.2%, respectively. None of vessel units in the dermal hypersensitivity reactions or normal skin contained more than 5 mast cells in vessel units ≤ 55μm and more than 10 mast cells in vessel units > 55μm. Cases of urticaria pigmentosa can be distinguished from other cutaneous eruptions containing mast cells using a simple counting technique on Giemsa stained sections.     

Immunohistochemical demonstration of migration inhibitory factor in different types of urticaria

Because urticarial lesions can persist for extended periods of time, we have investigated the histochemical expression of an antibody against the cytokine macrophage inhibitory factor in 23 patients with different types of urticaria. Positive staining of upper and middermal dendritic cells was noted in sections from all three biopsy specimens of acute urticaria, eight of chronic urticaria, and all six of urticaria pigmentosa lesions. In all but one biopsy specimen, endothelial cells reacted as well. In three sections (two chronic urticaria, one urticaria pigmentosa), luminal lining cells of sweat glands were also noted to stain positively. In contrast, lesional skin from all eight patients with pressure urticaria was negative, as was the clinically normal skin of all patients, with the exception of one patient with urticaria pigmentosa. The data suggest that cytokines may be involved in lesions of acute type immunologic processes and that they need not be expressed in delayed type reactions.     

Atypical pachydermatous cutaneous course of mastocytosis

We describe the case of a 75-year-old man first seen in our department 32 years ago for generalized yellowish erythematous papular lesions along with an attack of pruritus, tachycardia, and flushing. A diagnosis of urticaria pigmentosa was proposed on the basis of these symptoms and the results of skin biopsy. Periodic follow-up in the intervening years included serial laboratory analyses, skin biopsy, radiological studies, bone scintigraphy, and ultrasound of the liver and spleen, with no remarkable findings. The symptoms caused by release of mediators decreased progressively. In one of the most recent visits, bone marrow aspirate and biopsy were performed, revealing multifocal infiltrates of typical CD117+ mast cells. Consequently, the hematology department diagnosed indolent systemic mastocytosis. A number of marked cutaneous changes were observed during the follow-up period: the skin currently appears thickened, indurated, redundant, and grayish, with a pachydermatous appearance. This represents an extremely rare form of cutaneous involvement in mastocytosis and only 1 case has been described in the literature.     

The skin in mastocytosis.

The most frequent site of organ involvement in patients with any form of mastocytosis is the skin. Cutaneous expressions include urticaria pigmentosa, mastocytoma, diffuse and erythrodermic cutaneous mastocytosis, and telangiectasia macularis eruptiva perstans. The cutaneous lesions tend to appear early in life. Although urticaria pigmentosa has been reported in 12 pairs of twins and one set of triplets, the majority of affected individuals have no familial association. Most patients with systemic mastocytosis have skin lesions; however, an occasional patient will have systemic disease with no other skin features than flushing. In lesional cutaneous sites and in non-lesional skin, there is an increase in the number of mast cells. Electron microscopy shows quantitative differences between lesional skin mast cells from patients with and without systemic disease. The mast cells from adult patients with systemic disease have a larger mean cytoplasmic area, nuclear size, and granule diameter. The granules contain predominantly grating/lattice structures. The cutaneous mast cells contain tryptase and chymase. They retain their functional reactivities to relevant secretory stimuli, such as C3a, morphine sulfate, and calcium ionophore A23187. Lesional skin contains histamine, leukotriene B4, prostaglandin D2, 5-hydroxyeicosatetraenoic acid, platelet-activating factor, and heparin. Treatment of the cutaneous manifestations includes the use of H1 and H2 antihistamines, oral disodium cromoglycate, psoralens plus ultraviolet A photochemotherapy, and potent topical corticosteroid preparations.     

Analysis of c-kit exon 11 and exon 17 of urticaria pigmentosa that occurred in monozygotic twin sisters

Genomic DNA extracted from peripheral blood mononuclear cells of monozygotic twin patients with urticaria pigmentosa was investigated for mutations of proto-oncogene c-kit. Neither the patients nor their families had genomic mutations in exon 11 or exon 17 of c-kit. The patients did not have any systemic involvement or bone marrow abnormalities. There are indications that some genetic factors may participate in the pathogenesis of urticaria pigmentosa in monozygotic twins. In the present patients, factors other than genomic faults in exon 11 and exon 17 of c-kit may be responsible for the pathogenesis.     

Phenotypic characterization of skin lesions in urticaria pigmentosa and mastocytomas

In order to identify possible cellular abnormalities in human mastocytosis, sections from 13 urticaria pigmentosa lesions and 5 mastocytomas were compared with 5 normal skin specimens using histochemical, enzyme histochemical and immunohistochemical techniques. All toluidine blue-positive mast cells also reacted with FcRI and c-kit antibodies, almost all stained for tryptase, many for chymase and the myeloid workshop mast cell antibodies, few for FcRII and none for the proliferation marker Ki-67. Urticaria pigmentosa lesions contained fewer epidermal Langerhans cells and a lower percentage of avidin-positive mast cells than mastocytomas and normal skin. Mastocytomas exhibited generally weaker staining for mast cell markers and mostly lacked FcRI-bound IgE on mast cells and Langerhans cells, although the receptor was able to bind IgE in tissue sections. Most of the mast cell antibodies also reacted with other cell types. Only toluidine blue, avidin, tryptase and chymase stains were mast cell specific. Mast cells in mastocytosis thus differed only to a minor degree from normal mast cells, although distinct pathomechanisms may play a role in urticaria pigmentosa and mastocytosis.     

Cutaneous mastocytosis: A dermatological perspective

Mastocytosis is a rare disease characterised by expansion and collection of clonal mast cells in various organs including the skin, bone marrow, spleen, lymph nodes and gastrointestinal tract. The prevalence of mastocytosis has been estimated to be one in 10 000, while the estimated incidence is one per 100 000 people per year. Cutaneous mastocytosis is classified into (i) maculopapular cutaneous mastocytosis, also known as urticaria pigmentosa; (ii) diffuse cutaneous mastocytosis; and (iii) mastocytoma of the skin. In adults, cutaneous lesions are usually associated with indolent systemic mastocytosis and have a chronic evolution. Paediatric patients, on the contrary, have often cutaneous manifestations without systemic involvement and usually experience a spontaneous regression. Diagnosis of cutaneous mastocytosis may be challenging due to the rarity of the disease and the overlap of cutaneous manifestations. This short review describes pathogenesis and clinical aspects of cutaneous mastocytosis with a focus on diagnosis and currently available therapies.