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Scleromyxedema without monoclonal gammopathy: Diagnostic and therapeutic implications in the setting of subclinical hypothyroidism
*Corresponding author: Priyanka Kowe, Department of Dermatology, All India Institute of Medical Sciences, Nagpur, Maharashtra, India. priyanka.kowe@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Nayak P, Agrawal A, Kowe P, Mitra S. Scleromyxedema without monoclonal gammopathy: Diagnostic and therapeutic implications in the setting of subclinical hypothyroidism. CosmoDerma. 2026;6:14. doi: 10.25259/CSDM_208_2025
Abstract
Scleromyxedema (SM) is a rare fibromucinous disorder typically associated with monoclonal gammopathy, but atypical variants without paraproteinemia and with coexistent thyroid dysfunction challenge traditional diagnostic criteria. An elderly male presented with progressive pruritic skin thickening and waxy papules on the limbs and trunk, exhibiting classic SM signs including the “Shar-Pei sign” and “doughnut sign.” Laboratory evaluation revealed subclinical hypothyroidism (elevated thyroid-stimulating hormone and anti-thyroid peroxidase antibodies) but no paraproteinemia or other systemic abnormalities. Histopathology confirmed dermal mucin deposition, fibroblast proliferation, and fibrosis, supporting a diagnosis of atypical SM. The patient was treated conservatively with narrowband ultraviolet B (NB-UVB) phototherapy and levothyroxine (initially 25 µg/day, increased to 50 µg/day). Within 4 months, marked improvement was observed, including resolution of pruritus, flattening of papules, reduced induration, and restored mobility, sustained at 1-year follow-up. This case highlights that thyroid dysfunction should not preclude SM diagnosis, advocating for clinicopathologic correlation and longitudinal monitoring. Conservative therapies such as thyroid hormone replacement and NBUVB phototherapy may provide effective, accessible alternatives in select atypical cases, potentially expanding management options for this challenging condition.
Keywords
Doughnut sign
Narrowband ultraviolet B Phototherapy
Scleromyxedema
Shar-Pei sign
Subclinical hypothyroidism
INTRODUCTION
Scleromyxedema (SM) is a rare, chronic fibromucinous skin disorder characterized by a generalized eruption of symmetric waxy papules coalescing into indurated, scleroderma-like plaques with possible multisystem involvement. Atypical variants, including SM without paraproteinemia and with coexistent thyroid dysfunction, are increasingly recognized.[1,2] These “intermediate” presentations, with clinicopathologically confirmed SM, challenge the established diagnostic criteria and warrant classification as SM, even in the presence of thyroid disease.[3] We highlight a case of atypical scleromyxedema with subclinical hypothyroidism, characterized by the absence of monoclonal gammopathy and a significant response to thyroid hormone replacement and narrowband ultraviolet B (NB-UVB) phototherapy.
CASE REPORT
A 73-year-old Indian male presented with insidious-onset, progressive, intensely pruritic skin lesions and generalized skin thickening. He reported no systemic symptoms or significant medical or family history. Cutaneous examination revealed diffuse induration and tightening across the limbs and trunk, accompanied by symmetrically distributed, firm, waxy, and skin-colored papules on the dorsal hands and legs [Figure 1]. Notable findings included the “SharPei sign,” “Doughnut sign,” and restricted digital mobility [Figure 2]. Polarized dermoscopy displayed yellow-brown to whitish-yellow glistening areas, consistent with mucin deposition [Figure 3]. Laboratory investigations showed normal complete blood counts, renal function, and hepatic function. Thyroid function tests indicated subclinical hypothyroidism, with elevated thyroid-stimulating hormone ([TSH]; 11.76 µIU/mL) and anti-thyroid peroxidase antibodies (40 IU/mL), but normal free T3 and T4 levels. Serum and urine protein electrophoresis (including Bence Jones protein); antinuclear antibody; scleroderma-specific antibodies; rheumatoid factor; and viral serologies were negative. Chest radiography and abdominal ultrasonography were unremarkable. Histopathology confirmed the classic triad of scleromyxedema: Extensive dermal mucin deposition, prominent fibroblast proliferation, and dense fibrosis [Figure 4]. A multidisciplinary review confirmed the diagnosis of SM without paraproteinemia coexistent with subclinical hypothyroidism. The patient was treated with a conservative yet targeted approach by combining NB-UVB phototherapy with levothyroxine (25 µg/day). Within 4 months, he exhibited marked clinical improvement, including near-complete resolution of pruritus, flattening of papules, reduced induration, and restored digital mobility [Figure 5]. Follow-up thyroid function tests at 3 months revealed a TSH reduction to 6.5 µIU/mL, leading to an increase in levothyroxine to 50 µg/day, which has been maintained at the 1-year follow-up. NB-UVB phototherapy has been continued to date, with a therapy-free period of 2 weeks every 3 months.
- (a) Thickening of the skin over the dorsum of hands, (b) dorsum of fingers with shiny appearance.
- (a) Positive “Doughnut sign” over the hand dorsum (black arrow) and (b) positive “Shar pei” sign over the back (blue arrow).
- (a) Dermoscopy showing yellow white to light brown areas (black arrow), shiny skin (blue arrow), and (b) glistening appearance of the skin (black arrow) (DermLite, DL4 3G, ×10, polarized).
- (a) Histopathology showing dermal deposits in the upper dermis (blue arrow), fibroblast proliferation (black arrow), and fibrosis (red arrow) (H&E, ×40), and (b) mucin deposition in the upper to mid dermis (black arrow) (Alcian blue, ×100).
- Decrease in skin thickening and reduction in skin folds post-narrowband ultraviolet B phototherapy.
DISCUSSION
Diagnostic dilemma?
The diagnosis of SM in our patient presented a challenge due to the coexistence of subclinical hypothyroidism and the absence of monoclonal gammopathy. The traditional Rongioletti–Rebora diagnostic criteria emphasize monoclonal gammopathy and the absence of thyroid disease.[3] However, 10–20% of SM cases lack detectable paraproteinemia, advocating for a clinicopathologic diagnostic approach over strict adherence to the criteria. While some patients may seroconvert to paraproteinemia within years, others, like our patient, remain seronegative, highlighting the necessity for longitudinal monitoring of serum protein electrophoresis.[4-6] The presence of subclinical hypothyroidism further complicated the diagnosis, raising the possibility of thyroid dermopathy, which carries a relatively favorable prognosis compared to SM. However, thyroid dermopathy typically presents with localized skin thickening, a peau d’orange appearance, and mucin deposition primarily in the reticular dermis with minimal fibroblast proliferation. In contrast, our patient exhibited characteristic clinical, dermoscopic, and histopathological features of SM.[7] The absence of additional cutaneous signs of thyroid dysfunction, such as hyperhidrosis, thyroid acropachy, or dry, rough skin, further distinguished this case from thyroid dermopathy.[8]
Clinical applications and classification
Emerging evidence indicates that thyroid dysfunction, including hypothyroidism and autoimmune thyroiditis, should not serve as an exclusion criterion for SM diagnosis.[1,9,10] This perspective allows for subclassification of SM associated with thyroid disorders based on the presence or absence of paraproteinemia, as outlined in Tables 1[11] and 2.[12,13] To overcome the constraints of the Rongioletti–Rebora criteria, Nofal et al. [14] introduced a comprehensive framework that classifies SM and lichen myxedematosus (LM) according to clinicopathologic characteristics and disease severity, irrespective of thyroid involvement or paraproteinemia status [Table 3].[14] Consequently, patients with thyroid disease, such as the present case, may be designated as SM or “pure cutaneous LM” depending on the extent of involvement and systemic manifestations, rather than being dismissed as atypical SM. This approach facilitates ongoing surveillance for paraproteinemia and enhances management of atypical SM variants, potentially optimizing clinical outcomes. There is no universally effective treatment for SM. Intravenous immunoglobulin is a preferred first-line therapy for moderate to severe disease, but its use is often constrained by cost and accessibility. Although UVA1 remains the phototherapy of choice for fibrosing dermatoses, NB-UVB can be a rational first-line alternative considering the patient’s age and safety profile. Clinical improvement following thyroid hormone replacement has also been documented in several reports.[1,10] Further, thalidomide monotherapy has shown modest efficacy in paraprotein-negative or recalcitrant SM cases, while systemic steroids, methotrexate, or combinations thereof may be necessary for more refractory presentations. In severe or unresponsive disease, options including therapeutic plasma exchange for symptomatic relief, daratumumab, or even autologous stem cell transplantation have been explored.[4]
| Author (Year) | Age/Sex | Cutaneous features | Thyroid status | Treatment and outcome |
|---|---|---|---|---|
| Paraprotein status | ||||
| Martin-Ezquerra et al.(2006)[1] |
52/M | Localized papular mucinosis | Subclinical hypothyroidism | Thyroid therapy→Marked resolution |
| Not detected | ||||
| Schaeffer et al. (1983)[9] | NA | Pruritic, papular cutaneous lesions | Subclinical hypothyroidism | Levothyroxine+NB-UVB→resolved |
| Not detected | ||||
| Volpato et al. (2010)[10] | 40/F | Generalized papules and plaques | Subclinical hypothyroidism | Levothyroxine→Significant improvement |
| Not detected | ||||
| Li et al. (2014)[12] | 28/M | Generalized waxy papules | Overt hypothyroidism | Thyroxine; outcome not detailed |
| Not detected | ||||
| Present case | 73/M | Generalized waxy papules, sclerodermoid plaques | Subclinical hypothyroidism | Levothyroxine+NB-UVB→Near-complete remission at 6 months |
| Not detected |
NB-UVB: Narrowband ultraviolet B
| Author (Year) | Age/Sex | Cutaneous features | Thyroid status | Treatment and outcome |
|---|---|---|---|---|
| Paraprotein status | ||||
| Shenoy et al. (2019)[2] | 58/F | Widespread indurated, erythematous, thickened skin; confluent erythematous papules | Hashimoto thyroiditis | Intravenous immunoglobulin |
| Elevated IgG, gamma globulin, and M-spike in gamma region (detected 6 years after initial SM diagnosis) | ||||
| Laimer et al. (2007)[13] | 64/M | Erythematous induration, leonine facies, ectropion, joint contractures, sclerodactyly, hair loss, fatigue, and neuropathy | Autoimmune thyroiditis | Vincristine, idarubicin, dexamethasone, thalidomide (4 cycles; thalidomide withdrawn due to neuropathy); almost complete clinical remission |
| IgG-λmonoclonal gammopathy | ||||
| Taib et al. (2025)[14] | 70/F | Progressive cutaneous sclerosis on face, trunk, limbs; limited mouth opening, and dysphagia | Hashimoto thyroiditis | Systemic corticosteroids, then IVIG (4 cycles); no improvement; disease progressed; and patient died 5 months after last cycle |
| IgG kappa monoclonal gammopathy |
IVIG: Intravenous immunoglobulin
| (A) Constant features 1. Firm, waxy, closely set papules that may coalesce into indurated nodules or plaques 2. Diffuse dermal mucin deposition and fibroblast proliferation, with or without fibrosis |
| (B) Variable associated features 1. Monoclonal gammopathy 2. Thyroid disorder 3. HIV and hepatitis C virus infections 4. Peripheral eosinophilia 5. Thymic carcinoma and hepatocellular carcinoma |
CONCLUSION
This case emphasizes that thyroid dysfunction should not exclude a diagnosis of scleromyxedema. Instead, clinicopathologic correlation and longitudinal monitoring are essential, and conservative therapies such as thyroid hormone replacement and NB-UVB phototherapy may offer significant clinical benefit in selected patients.
Ethical approval:
The Institutional Review Board approval is not required.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
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