Unusual granulomatous variant of scleromyxedema

Scleromyxedema histopathologically mimicking hypercellular fibrous papules (angiofibomas): Case report of an unusual histopathological presentation

Scleromyxedema (SMX) is an inflammatory condition of unknown etiology strongly associated with monoclonal gammopathy. Classical histopathology of SMX is characterized with the triad of diffuse mucin deposits, increased amount of collagen, and presence of stellate fibroblasts. Herein, we report an unusual histopathological variant of SMX in a 41-year-old female with lesions of the nose histopathologically mimicking cellular angiofibromas. The dome-shaped papules were characterized by increased collagen bundles and fascicles of spindle cells. Widened vessels were seen at the periphery of the proliferation. Cells expressed CD68. Factor XIIIa was expressed only by dendritic cells. The mucin was highlighted with colloidal iron. In sum, we draw attention to this unusual variant of SMX, which should be suspected in a setting of multiple "angiofibromas/fibrous papules" on the face with presence of mucin.

[Granulomatous reaction pattern of the skin : Interstitial granulomatous dermatitis - lymphoma - vasculitis]

A particular diagnostic situation in the classification of a granulomatous dermatitis results when no circumscribed granulomas but instead a diffuse interstitial histiocytic inflammatory infiltrate, a granulomatous vasculitis or a neoplastic lymphocytic infiltrate is found. Interstitial granulomatous dermatitis was originally described in patients with arthritis. Later, it was recognized that there are also associations with other usually immunological diseases. Differentiating between interstitial granulomatous dermatitis and the interstitial form of granuloma annulare, early morphea and variants of borreliosis or scleromyxedema as well as interstitial granulomatous drug reaction can be very difficult. In long-standing cutaneous granulomatous infiltrates, T‑cell lymphoma should be excluded. Occasionally only a small number of atypical lymphocytes can be found. The detection of a monoclonal T‑cell expansion is then particularly helpful. Only recently, a CD8-positive granulomatous cutaneous T‑cell lymphoma was described which occurred in patients with immunodeficiencies. A granulomatous vasculitis in the skin is extremely rare. According to the Chapel Hill classification from 2012, systemic granulomatous vasculitis is equated with giant cell arteritis. Extracutaneous large arteries are involved. On rare occasions, involvement of the temporal artery can result in skin necrosis. More commonly granulomatous infiltrates in combination with vasculitis can be observed, whereby various infectious diseases, sarcoidosis and nodular vasculitis should be considered. Granulomatosis with polyangiitis (formerly Wegener's granulomatosis), presents in the skin as leukocytoclastic vasculitis. Here granulomas are extremely rare.

[Scleromyxedema as a systemic disease of glycosaminoglycan accumulation]

Scleromyxedema is a rare mucinosis with a primary skin lesion due to diffuse mucin deposition, sclerosis, and lichenoid eruptions in the absence of hypothyroidism. The paper describes scleromyxedema cases and gives recommendations for the histological diagnosis of the disease by histochemical reactions to detect acid and neutral glycosaminoglycans.

[Is scleromyxedema a skin problem or systemic pathological process?]

Scleromyxedema is regarded as a rare cutaneous mucinosis from a group of lichen myxedematosus characterized by diffuse mucin deposition, sclerosis, and lichenoid eruptions in the absence of thyroid disease. The paper discusses the pathogenesis of the disease and histological changes in tissues. It underlines the need for using histochemical tests to identify acidic and neutral glycosaminoglycans and gives a differential diagnosis of this disease.

[Atypical scleromyxedema with a granulomatous histological pattern and delayed sclerosis]

BACKGROUND

Papular mucinosis is characterised by primary mucin deposition in the dermis. The classification distinguishes between the localised form and the systemic form, which alone can result in complications, but this classification occasionally proves to be inadequate. Herein we report the progression of papular mucinosis, initially atypical due to the absence of cutaneous sclerosis and of misleading granulomatous histological features, which subsequently developed into characteristic scleromyxedema.

PATIENTS AND METHODS

A 55-year-old male developed a rash comprising countless acral papules. Several biopsies were necessary before a diagnosis of papular mucinosis was made, due to the initial granulomatous appearance at histology. Tests showed monoclonal immunoglobulin of indeterminate significance, but, due to the absence of cutaneous sclerosis, we were able to conclude on typical localised papular mucinosis. Two years later, extensive sclerotic induration of the skin appeared and the diagnosis was modified to one of scleromyxedema. Treatment with intravenous immunoglobulins was given and proved efficacious, but relapse occurred on discontinuation of the therapy.

DISCUSSION

Papular mucinosis is a rare disease of unknown physiopathology. The disease classification distinguishes between the localised and systemic forms, but it occasionally proves to be inadequate. Our case suggests a continuum between the localised and systemic forms of the disease. Further, the initial biopsies of acral papules in our patient had a misleading granulomatous appearance, as has been reported numerous times for the systemic forms. This granulomatous histological variant thus appears to constitute a diagnostic criterion for scleromyxedema.

[Dermatological manifestations of monoclonal gammopathies: contribution of cutaneous histopathology]

Skin manifestations associated with monoclonal gammapathy are common and can present with various clinical and pathological aspects. They can be the first events leading to the diagnosis of monoclonal gammapathy. They may be present either as specific lesions, including lymphoplasmacytic or pure plasma cell neoplastic infiltrates and monoclonal immunoglobulin deposits, or as non-specific dermatitis, such as leukocytoclastic vasculitis, neutrophilic dermatoses, mucinoses or xanthomatosis, giving little clues for the diagnosis of the underlying disease.

An unusual histologic variant of necrobiotic xanthogranuloma

Necrobiotic xanthogranuloma (NXG) usually shows a stereotypical histopathologic presentation. However, few unusual cases have been published. We present a patient with NXG showing exceptional histopathologic features. NXG in our patient presents with exclusively dermal granulomatous inflammation mimicking interstitial granuloma annulare. Not only subcutaneous involvement, but also, evident zones of degenerated collagen, foam cells, and cholesterol clefts were missing. Moreover, the case shows overlaps with recently published granulomatous scleromyxedema. Some common clinical and histopathologic features of NXG and scleromyxedema might be based on shared underlying paraproteinemia.

[Atypical papular mucinosis with initial histological findings evocative of granuloma annulare]

BACKGROUND

Papular mucinosis is characterized by primary reticular dermal mucin deposition in the absence of any thyroid abnormalities. There is extensive clinical variety in this disease, from benign localized forms to generalized forms, on occasion lethal. The current classification was established in 1991 in order to allow identification of these generalized forms of the disease and help ensure a better therapeutic approach. We report the case of a patient with atypical papular mucinosis having initial histological features consistent with granuloma annulare.

PATIENTS AND METHODS

A 55-year-old man consulted for a papular eruption of the hands. A diagnosis of granuloma annulare was initially made because of misleading histological findings. However, the eruption spread to the inner thighs and the hypogastric area despite dermocorticoid therapy. Laboratory evaluation showed a monoclonal gammopathy. Further biopsies revealed diffuse dermal mucin deposits. We finally concluded on atypical localized papular mucinosis.

DISCUSSION

Papular mucinosis is a rare disease and its physiopathology remains to be elucidated. The diagnostic criteria are sometimes inadequate, and its classification includes both atypical and intermediate forms. Our case belongs to the latter class because of its extensive and unusual topography, and its association with a monoclonal gammopathy. Although granuloma annulare is not a classical differential diagnosis, two other cases with similar histological findings have already been published.

Scleromyxedema with an interstitial granulomatous-like pattern: a rare histologic variant mimicking granuloma annulare

Scleromyxedema is the generalized and sclerodermoid form of lichen myxedematosus. Its typical histological features include a diffuse deposition of mucin in the papillary and mid reticular dermis, an increased of collagen deposition, and a proliferation of irregularly arranged fibroblasts. We describe a 76-year-old man presenting with scleromyxedema associated with IgGlambda monoclonal gammopathy whose biopsy showed histological features of an interstitial granulomatous-like process consistent with interstitial granuloma annulare. The significance of these unusual granulomatous findings in the setting of scleromyxedema are unknown and have been described only once in the literature. This observation expands the spectrum of scleromyxedema and highlights the difficulty in diagnosing this disabling condition.