The ultrastructure of granuloma annulare

Spatial transcriptomics reveals organized and distinct immune activation in cutaneous granulomatous disorders

BACKGROUND

Noninfectious (inflammatory) cutaneous granulomatous disorders include cutaneous sarcoidosis (CS), granuloma annulare (GA), necrobiosis lipoidica (NL), and necrobiotic xanthogranuloma (NXG). These disorders share macrophage-predominant inflammation histologically, but the inflammatory architecture and the pattern of extracellular matrix alteration varies. The underlying molecular explanations for these differences remain unclear.

OBJECTIVE

We sought to understand spatial gene expression characteristics in these disorders.

METHODS

We performed spatial transcriptomics in cases of CS, GA, NL, and NXG to compare patterns of immune activation and other molecular features in a spatially resolved fashion.

RESULTS

CS is characterized by a polarized, spatially organized type 1-predominant response with classical macrophage activation. GA is characterized by a mixed but spatially organized pattern of type 1 and type 2 polarization with both classical and alternative macrophage activation. NL showed concomitant activation of type 1, type 2, and type 3 immunity with a mixed pattern of macrophage activation. Activation of type 1 immunity was shared among, CS, GA, and NL and included upregulation of IL-32. NXG showed upregulation of CXCR4-CXCL12/14 chemokine signaling and exaggerated alternative macrophage polarization. Histologic alteration of extracellular matrix correlated with hypoxia and glycolysis programs and type 2 immune activation.

CONCLUSIONS

Inflammatory cutaneous granulomatous disorders show distinct and spatially organized immune activation that correlate with hallmark histologic changes.

Scanning electron microscopy of granuloma annulare

Light microscopy of granuloma annulare shows mucin deposition with lympho-histiocytic infiltrate. We describe the ultrastructural three-dimensional aspects of a typical case of granuloma with characteristic histopathological findings. At the ultrastructural level, affected collagen bundles and granular mucin deposition were observed. Round cells corresponding to lymphocytes were identified. Bigger oval cells, corresponding to isolated or palisading histiocytes were also found. The ultrastructural aspects overlap with light microscopy and contribute to its iconographic documentation.

Collagen-elastic tissue changes and vascular involvement in granuloma annulare: a review of 35 cases

BACKGROUND

The pathogenesis of granuloma annulare (GA) is unclear. Collagen fiber degeneration is commonly reported, and there are several conflicting studies on elastic fiber and vascular changes associated with GA. In this study, we aimed to evaluate histopathologic characteristics, collagen and elastic tissue changes and vascular changes in GA.

METHODS

Clinical records of 35 GA patients were examined alongside serial sections of 38 biopsy specimens from these patients. New sections of biopsy tissue were stained with hematoxylin and eosin, Verhoeff-van Gieson or Alcian blue and then evaluated.

RESULTS

Four different histopathologic patterns were observed: interstitial (57.9%), palisadic granulomatous (26.3%), sarcoidal granulomatous (5.3%) and mixed (10.5%). Dermal mucin deposition was determined in 84.2% of specimens. Solar elastosis was observed in only seven specimens, and elastophagocytosis was observed in only two specimens. Collagen and elastic tissue damages were consistent findings in all biopsy specimens. Fibrin thrombi and vasculitic changes were not found in any of the specimens from this patient group.

CONCLUSIONS

Elastic and collagen fiber damage are the main accompanying features of GA, which may develop from delayed-type hypersensitivity. Vasculitis does not appear to be a major causative process. Sun exposure also seems to have no major effect on the formation of GA but can be one of the stimulants or predisposing factors.

Low serum insulin values in children with multiple lesions of granuloma annulare: a prospective study

BACKGROUND

The relationship between granuloma annularae (GA) and diabetes mellitus (DM) is controversial.

OBJECTIVE

To investigate the relationship between multiple lesions of GA and carbohydrate metabolism in children.

SUBJECTS AND METHODS

Fifteen children (seven boys, eight girls, mean age 4.8 years) with five or more lesions of GA were evaluated. A personal and family history of DM or other autoimmune diseases was obtained and the glycaemic and insulin response during an oral glucose tolerance test (OGTT) was determined. Thirteen children with a negative personal and family history of DM served as controls for the OGTT and 100 other children as 'clinical controls'.

RESULTS

At the 30-min sampling of the OGTT the mean insulin values were comparable in GA children and controls (P=0.1), while the mean glucose values were significantly higher in GA children than in controls (P=0.005). All other insulin values during the OGTT were significantly lower in GA children than in controls, while all other glucose values were comparable in GA children and controls with all indices applied. Eleven out of 15 GA children had a positive family history of DM (73.3% vs. 16% of the clinical controls; P<0.0001).

CONCLUSION

Multiple lesions of GA in children are associated with significantly lower serum insulin values than in controls and mildly impaired glucose tolerance.

Granuloma annulare: an elastic tissue disease? Case report and literature review

Granuloma annulare (GA) is a condition characterized by the presence of palisading granulomas usually in the dermis. Traditionally, the histopathological changes are described as consisting of focal degeneration of dermal collagen fibers. However, no convincing evidence for such alteration is found in the literature. A histopathological study was done to ascertain the nature of the dermal abnormality. Ten skin biopsies showing lesions of GA were studied by light and electron microscopy. On light microscopy, all lesions showed focal dermal degeneration with near total loss of elastic fibers. Ultrastructural examination in nine cases demonstrated degenerated elastic fibers with loss of peripheral microfibrils and abnormal elastic matrix. The degenerated elastic fibers were surrounded by intact collagen fibers. These findings show that the main alteration in GA is elastic fiber degeneration and strongly suggest that the primary target leading to the development of this disorder is injury to the elastic tissue.

Collagen synthesis in granuloma annulare

Previous research has demonstrated active collagen synthesis in granuloma annulare (GA), a mainly degenerative disease of the skin. The present investigation is aimed to characterize details of the collagen synthesis and its regulation. Northern and in situ hybridization techniques and immunohistochemical methods are used to identify type I and type III collagen synthesis, regulation-associated polypeptides TGF-beta, Il-1 alpha, and Il-1 beta and an extracellular matrix protein tenascin, as well as lymphohistiocytic cells present in GA lesions. High mRNA levels of both pro-alpha 1 (I) and pro-alpha 1 (III) collagens were detected in GA lesions. In situ hybridization with cDNA probes revealed active fibroblasts with signals for both type I and III collagen mRNA around GA lesions. Some TGF-beta expression was found within the areas of inflammatory cells. Immunohistochemically, most of the mononuclear/lymphatic cells were CD3+ T cells. The helper/inducer phenotype (CD4+) was common among them, but there were no T-suppressor (CD8) cells. CD1+ cells were few in number, as were cells with activation or proliferation markers (CD26, CD30, and Ki67 antigens). Il-1 alpha- and Il-1 beta-positive lymphocytes/monocytes as well as interleukin-2 receptor containing cells were detected around the lesions, i.e., in the same areas as collagen-synthesizing fibroblasts. Another possible association with the regulation of collagen synthesis was the finding of an accumulation of tenascin, a growth-promoting extracellular matrix protein, in the surroundings of the GA lesions. We suggest that the firmly established and seemingly well-regulated type I and type III collagen synthesis presents a reparative phenomenon in the cutaneous lesions of GA.

Epidermal dendritic S100 positive cells in necrobiosis lipoidica and granuloma annulare

Using an antibody to S100 protein, the number of dendritic cells above the basal layer in the epidermis was assessed in necrobiosis lipoidica and granuloma annulare. A statistically significantly higher number of these cells was found within the epidermis in necrobiosis lipoidica compared with granuloma annulare and normal skin. The numbers were similar to those seen in sarcoidosis and tuberculous reactions in the skin, which raises the possibility of an immune pathogenesis for necrobiosis lipoidica.

Bilateral idiopathic inflammation of the optic nerve sheaths. Light and electron microscopic findings

Idiopathic perioptic neuritis is a term used to describe noninfectious inflammatory disorders of the optic nerve sheaths, the causes of which are unknown. In the following report, a 68-year-old woman with bilateral visual loss was found to have chronic inflammation with necrobiotic granulomas of her optic nerve sheaths. The patient, who had no systemic condition known to be associated with necrobiotic granuloma, lost vision from infarction of the optic nerve parenchyma and from compression due to thickened meninges. Although there are similarities between the inflammatory reaction in this case to the necrobiotic dermatoses, the pathogenesis of this condition remains obscure.

Generalized granuloma annulare: histopathology and immunopathology. Systematic review of 100 cases and comparison with localized granuloma annulare

Some form of collagen alteration (necrobiosis) was observed in 53% of patients with generalized granuloma annulare and in 79% of patients with localized granuloma annulare. Fragmentation of collagen bundles was the most common single type of collagen abnormality in both groups. Collagen sclerosis, accompanied by a strong palisading pattern of histiocytes, was more frequent in localized granuloma annulare. Results of microdroplet lipid staining were positive in 80% of annulare cases and 39.3% of nonannulare cases of generalized granuloma annulare. Inflammatory cells were confined to peripheral perivascular lymphocytes; bandlike granuloma below the epidermis was observed. Positive results of direct immunofluorescence tests in 12 of 23 patients with generalized granuloma annulare suggested that fibrin deposition in areas of altered collagen is less frequent in the generalized than in the localized form, a possible reflection of the lower rate of histologic collagen alteration in that group. Lymphohistiocytic granuloma with various degrees of collagen degeneration, microdroplet lipid accumulation, and mucin deposition form the basic pathologic description of granuloma annulare.

Granuloma annulare, necrobiosis lipoidica, and diabetic disease

One hundred sixteen patients with granuloma annulare and necrobiosis lipoidica were studied. The relationship of these two disorders with diabetes mellitus suggests that atypical granuloma annulare could be linked to necrobiosis lipoidica, toward which it progresses.

Periocular granuloma annulare

A 2-year-old boy presented with a 3-month history of nontender masses involving the right superotemporal orbit and scalp. Over the three-week period before presentation he also developed nodules on his wrist, abdomen, and buttocks. The remainder of the ocular and general physical exam was unremarkable. A biopsy of the right orbital mass demonstrated stellate areas of collagen necrosis surrounded by pallisading epithelioid histiocytes and scattered multinucleated giant cells. Special stains for connective tissue mucin were positive in the areas of necrosis. The diagnosis reached pathologically and clinically were that of pseudorheumatoid nodules and granuloma annulare syndrome respectively. These two diagnostic terms have been used independently in the ophthalmologic and dermatologic literature, despite the identical histologic and clinical behaviors seen by both medical groups. A unified nomenclature system of pseudorheumatoid nodule for the histopathology of an individual lesion and granuloma annulare for the syndrome is suggested.

Membrane activity in juvenile xanthogranuloma

In a case of juvenile xanthogranuloma in an early stage, electron microscopic examination revealed membrane activity resulting in complex interdigitations with subsequent transformation into aggregated cytoplasmic vesicles. Similar membrane complexes were encountered in multinucleated giant cells and they may be a result of endocytosis of remnants of cell membranes of fused macrophages. Other findings were "virus-like inclusions" in histiocytes and giant cells, intracytoplasmic collagen in fibroblasts and "cross-banded filamentous aggregations".

Granuloma annulare

Granuloma annular (GA) is a benign inflammatory skin disease usually localized to the distal extremities, although generalized, perforating, and subcutaneous variants have also been identified. A regular histopathologic feature is the presence of mononuclear cells, often in palisading array, around foci of altered collagen. The clinical and histologic features of each subtype of GA are discussed along with a differential diagnosis. A variety of remedies have been used to treat GA, but efficacy is hard to define in a disease in which spontaneous resolution is usual outcome. GA has not been conclusively linked either to diabetes or solar radiation. Recent data suggest a role for vascular injury or delayed-type hypersensitivity in the pathogenesis, but the cause of GA remains obscure.