Morphological Diversity of Pretibial Myxedema and Its Mechanism of Evolving Process and Outcome: A Retrospective Study of 216 Cases

Abstract

Background. Pretibial myxedema (PTM) is a rare dermopathy. The morphologic features and mechanism of its evolving process are not reported in large case series. Methods. 216 cases with PTM were retrospectively reviewed to analyze demographics, history, lesional morphology and its evolving process, histopathology and immunohistochemistry, serum TRAb levels, treatment, and outcome. Results. First appearing lesions evolved into 6 variants that were correlated with serum TRAb levels. Subvariants were caused by different kinds and frequencies of local trauma. The evolving process could be classified into 4 stages that were correlated with serum TRAb levels and perivascular infiltration of CD8+ and CD4+ lymphocytes. Serum TRAb levels at remission and in nonrecurred cases became lower than those before therapy and in recurred cases, respectively, but increased when PTM relapsed. TRAb level in nodule variant went down invariably with the extension of course and its autoimmune activity had a trend to stop but in other 5 variants TRAb levels fluctuated. Their autoimmune activities had no trends to stop and clinically worsen through intermittent repeats of active and stable stages. Conclusions. In the chronic course of PTM, nodule variant is self-limited and other 5 variants are not self-limited. PTM needed early treatment to avoid severe variants.

Thyroid-Stimulating Hormone Receptor Autoimmunity and Local Factors in Multiple Risk Factors Are Mainly Involved in the Occurrence of Pretibial Myxedema

“…A definite diagnosis for PTM was made under the background of thyroid diseases or thyroid disease history, the presence of typical skin lesions, or atypical skin lesions (atypical locations and atypical appearances) plus histopathology of mucinous degeneration and positive Alcian blue staining in the dermis (modified from [6] and [14]). GD was diagnosed on the basis of clinical and/or biochemical evidence of thyrotoxicosis plus one or more of the following features: serum TRAb positive, thyroid-associated ophthalmopathy and/or dermopathy and/or acropachy, hypoechoic and increase in vascularity shown by thyroid ultrasound with Doppler, and diffuse elevated radioactive iodine uptake (RAIU).…”

“…Multiple modalities of PTM treatment have been reported that include minimizing risk factors (smoking, obesity), topical steroids, intralesional steroids (triamcinolone, betamethasone) [34], plasmapheresis, intravenous immunoglobulin (IVIg), surgery [35], UVA1, compression bandages, and massage therapy. Glucocorticoid inhibiting TSHR autoimmunity and HA synthesis can lower serum TRAb levels and improve PTM [6,36]. Rituximab (RTX) and IVIg have recently been reported to achieve improvement or stability of PTM.…”

“…A few gradually become hardened and enter a sclerotic stage, and in even fewer Risk Factors for PTM J Clin Med Res. 2020;12 (11):711-723 cases, nodule variants disappear spontaneously [6]. Histopathologically, PTM is characterized by significant thickening of the dermis due to excessive deposits of mucopolysaccharides (such as hyaluronan (HA) and chondroitin sulfate) [7].…”

An atypical presentation of pretibial myxedema in a euthyroid patient with absent antithyroid autoantibodies

“…This progression was correlated with TSH-R antibody titers and the degree of perivascular lymphocytic infiltration. 7 …”

Intralesional and topical glucocorticoids for pretibial myxedema: A case report and review of literature

“…Once every seven days is a better regimen. Lan et al[ 10 ] also performed a retrospective study. An intralesional glucocorticoid was used and the dosage of triamcinolone acetonide acetate was 50 mg/5 mL.…”