Cutaneous mucinosis clinically masquerading as cutaneous lymphoma and associated with undifferentiated connective tissue disease

Dear Editor,

Cutaneous mucinosis (CM) is characterised by mucin deposition in the dermis and can be classified as either primary or secondary. It poses a significant diagnostic challenge due to its heterogeneous clinical presentation.¹ It has been reported in association with various connective tissue disorders (CTDs) like systemic lupus erythematosus (SLE), dermatomyositis, systemic sclerosis, and rheumatoid arthritis. We hereby describe an unusual presentation of papulonodular CM in the form of widespread, rapidly enlarging, woody hard plaques and nodules associated with undifferentiated CTD in a middle-aged woman.

A 46-year-old woman presented with rapidly progressing, multiple asymptomatic erythematous plaques over the face, trunk, upper and lower limbs for the last 6 months. She complained of pain in the small joints of her hands, feet, knees and ankles, associated with morning stiffness. She was a known case of seizure disorder for 2 years, on treatment with oral carbamazepine. There was no history of constitutional symptoms, photosensitivity, or Raynaud’s phenomenon. Cutaneous examination revealed multiple well-defined erythematous to skin-coloured, woody hard indurated plaques and nodules, with the majority exhibiting central duskiness and depression and peau d’orange appearance, ranging in size from 1 cm × 1 cm to 15 cm × 5 cm on the face, neck, trunk, upper and lower limbs [Figures 1a-c]. There was no regional lymphadenopathy. Systemic examination was unremarkable. Based on clinical findings, differential diagnoses of cutaneous lymphoma, cutaneous metastasis, non-Langerhans cell histiocytosis, sarcoidosis, and tumid lupus erythematosus (LE) were considered. A punch biopsy was performed from the abdominal plaque. Histological examination revealed mild hyperkeratosis and flattening of rete ridges. There was abundant mucin deposition in papillary and reticular dermis with intervening proliferating fibroblasts and thickened collagen fibres. Mild perivascular lymphocytic infiltrate was present [Figures 2a-b]. Mucin deposits were highlighted on an alcian blue stain [Figure 2c]. On immunological profile, she had positive rheumatoid factor, anti-nuclear antibody (2+ speckled pattern), and anti-Sjogren’s syndrome related antigen-A (SS-A) 4+. Routine haematological and biochemical tests, thyroid function tests, complement levels, and muscle enzymes were within normal limits. Serum and urine electrophoresis did not show any abnormality. Contrast-enhanced computed tomography scan of the chest and abdomen, echocardiogram, and radiographs of hands, feet, knee, and ankle joints were unremarkable. Based on the above findings, a final diagnosis of papulonodular CM associated with undifferentiated CTD was made.

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Figure 1a:

Skin-coloured to erythematous indurated plaque with dusky centre on the left retroauricular area.

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Figure 1b:

Giant erythematous plaque with dusky centre on the lower back, along with a few smaller lesions in the vicinity.

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Figure 1c:

Multiple erythematous plaques with central duskiness and some with peau d’orange appearance on the abdomen and even involving the umbilicus. A few skin- coloured nodules are also present.

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Figure 2a:

Mild hyperkeratosis, flattening of rete ridges, and abundant bluish-grey deposits in papillary and reticular dermis (Haematoxylin and eosin, 40x).

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Figure 2b:

Dermis shows bluish-grey stringy material suggestive of mucin, with intervening proliferating fibroblasts and thickened collagen fibres and mild perivascular lymphocytic infiltrate (Haematoxylin and eosin, 200x).

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Figure 2c:

The mucin deposits are highlighted on an alcian blue stain (Alcian blue, 40x).

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Primary mucinosis includes mainly lichen myxedematous, reticular erythematous mucinosis, scleredema, self-healing cutaneous mucinosis, follicular mucinosis, mucinosis associated with altered thyroid function and papulonodular mucinosis associated with CTDs. Lichen myxedematous is classified into two main subsets: generalised papular and sclerodermoid form, called scleromyxedema and localised papular form.¹ Scleromyxedema is typically associated with monoclonal gammopathy, multiple organ involvement, and the absence of thyroid disorder.² In contrast, this patient presented with rapidly evolving generalised woody hard indurated plaques and nodules without any evidence of monoclonal gammopathy. Additionally, she had joint pains and serological evidence of CTD; however, she did not fulfil the diagnostic criteria for any CTD. Among CTDs, papulonodular mucinosis is most commonly reported with LE and presents as skin-coloured to erythematous papules, nodules or less frequently plaques with dusky and depressed centre on the V area of the chest, back and upper limbs, which may accompany or precede the disease.^3,4 Plaque-like cutaneous lupus mucinosis has been described as the first sign of SLE.⁵ Tumid LE can be a close differential in such a case. It usually appears as urticaria-like erythematous oedematous papules and plaques, commonly on photo-exposed areas like the face and neck, and there is usually a history of photosensitivity. While this patient had erythematous to skin-coloured plaques and nodules with dusky center and peau d’orange appearance, mainly on the photo-protected sites. In addition, histopathology of tumid LE besides mucin, also shows superficial and deep perivascular and periadnexal cuffed lymphocytic infiltrate, which were absent in this patient. Various conditions associated with plaque type CM include autoimmune CTDs (SLE, mixed connective tissue disease, scleroderma, dermatomyositis), thyroid disorder (hypo and hyperthyroidism), malignancies including colon and breast adenocarcinoma, pancreatico-biliary tumours and paraproteinemia.

Management depends on the severity and extent of lesions. Treatment options include corticosteroids, antimalarials, immunosuppressants, and intravenous immunoglobulins (IVIG), although no standard treatment exists due to the rarity of this condition.⁶ Magdaleno-Tapial et al.⁷ reported an excellent response to IVIG in a case of plaque-like CM, unresponsive to systemic corticosteroids and was intolerant to hydroxychloroquine. We started our patient on prednisolone 50 mg and hydroxychloroquine 400 mg, and planned her for IVIG. However, she was lost to follow-up.

This case highlights the atypical presentation of CM as rapidly progressing widespread erythematous indurated plaques and nodules mimicking cutaneous lymphoma, in the setting of undifferentiated CTD.