2016Letter to the editor. DOI: 10.1111/jdv.1400

ALMEIDA JUNIOR, L. H.

CAMIÑA, R. H.

CASTRO, L. A. S. de

CUNHA FILHO, R. R. DA

SABEI, J. D.

Letter to the editor. DOI: 10.1111/jdv.1400

LAReferencia - Red Federada de Repositorios Institucionales de Publicaciones Científicas Latinoamericanas

Pretibial myxoedema: a case report with scanning electron microscopy.

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LETTER TO THE EDITORPretibial myxoedema: a casereport with scanning electronmicroscopyEditorPretibial myxoedema (PTM) results from the accumulation ofhyaluronic acid in the dermis and subcutis and is commonlyassociated with Graves’ disease (GD). It occurs in up to 5% ofpatients with GD and in 13% of patients with GD and ophthal-mopathy. PTM occasionally occurs in thyrotoxicosis but is muchless frequent in patients with Hashimoto thyroiditis, primaryhypothyroidism and euthyroidism. Clinically, PTM may mani-fest as waxy, erythematous nodules or plaques, often with evi-dent follicular openings located on the tibial region. Diagnosis isconfirmed by light microscopy.1 We examined the dermis of aPTM case with a scanning electron microscopy (SEM), whichidentified unreported findings of this condition.A 39-year-old White male patient, diagnosed with Graves’disease with thyrotoxicosis and exophthalmos, under treatmentwith propylthiouracil, presented with waxy, yellowish or slightlyerythematous plaques, with prominent follicular openings onthe anterior aspect of his legs (Fig. 1a). After 6 months, heunderwent radioactive iodine therapy progressing to hypothy-roidism. Histopathological samples obtained by incisionalbiopsy of lesions revealed accumulation of mucin in reticulardermis leading to separation of collagen bundles. Star-shapedfibroblasts were seen under haematoxylin and eosin staining(H&E) (Fig. 1b) and more evident with Alcian Blue (Fig. 1c).Intralesional infiltration with triamcinolone was used with sig-nificant improvement and subsequent partial relapse.On examining the dermal surface of biopsy punch using SEM,three distinct areas could be visualized: areas with normal colla-gen bundles without deposit (9650) (Fig. 2a), a transitional areawith normal and slightly distorted collagen bundles (arrow) andmucin deposition (2.2009) (Fig. 2b). In the most affected area,in the deep reticular dermis, the deposit was tightly packed, cov-ering, separating and disrupting the bundles and the collagenfibres (8509) and (8.5009) (Figs. 2c,d).Light microscopy can establish PTM diagnosis. The depositcan be visualized using special staining (Alcian Blue, colloidaliron or toluidine blue), which produces spaces among the colla-gen fibres. Normal amount of fibroblasts can be evidenced, someof them with a star-shaped outline.2Even though the exact cause is still elusive, it is knownthat besides immunological effects, mechanical factors(a) (b)(c)Figure 1 (a) Erythematous plaques on the anterior aspect of thelegs (b) Normal epidermis; dermis with extensive interstitial depos-its of mucin (amorphous, amphophilic material), permeating andpushing away the collagen fibres, more evident in the reticulardermis HE-409 (c) normal amount of star-shaped fibroblasts,Alcian Blue 4009.(a) (b)(c) (d)Figure 2 Scanning electron microscopy (a) normal area with col-lagen-forming bundles (9650), (b) transition of normal bundles (ar-row) to the affected area (92.200); (c) affected area with ‘packing’of collagen with some loose bundles and fibres (9850); (d) highermagnification showing the ‘packing’ of collagen by deposits(98.500).© 2016 European Academy of Dermatology and VenereologyJEADV 2016JEADVcontribute to the formation of PTM. Antibodies bind to thy-roid-stimulating hormone receptor and stimulate the dermalfibroblasts, increasing the production of glycosaminoglycans.The accumulation of these polysaccharides separates the colla-gen fibres and obstructs the lymphatic vessels, causingoedema. The predisposition of the pretibial region could beexplained by trauma.2Pretibial myxoedema has been already examined by transmis-sion electron microscopy. It was observed that the bundles andthe collagen fibres were separated by wide electron-lucent gaps.Fibroblasts have a star-shaped appearance with extensive forma-tion of cytoplasmic processes.1Scanning electron microscopy has been shown to be help-ful in studying the ultrastructure of dermal diseases withdeposits, as previously reported in other studies. In thisreport, we were able to reveal the accumulation of mucin inreticular dermis. It separates, disrupts and covers most of thecollagen fibres, but it does not assume a peculiar morphologi-cal appearance as it does in amyloidosis (stone-like appear-ance)3 and in lichen sclerosus and atrophicus (a pearlnecklace appearance).4 SEM is not used routinely; however itcan provide additional ultrastructural information of condi-tions with dermal involvement.R.R. da Cunha Filho,1,* H.L. de Almeida Jr,2 J.D. Sabei,1R.H. Cami~na,3 L.A.S. de Castro41Department of Dermatology, Western University of Santa Catarina,Joacaba, Brazil, 2Department of Dermatology, Federal University ofPelotas and Catholic University of Pelotas, Pelotas, Brazil, 3Department ofPathology, Western University of Santa Catarina, Joacaba, Brazil,4Laboratory of Electron Microscopy, Embrapa Clima Temperado (BrazilianAgricultural Research Corporation), Pelotas, Brazil*Correspondence: R.R. da Cunha Filho. E-mail: robertodermatolo-gista@yahoo.com.brReferences1 Rongioletti F, Rebora A. Mucinoses. In: Bolognia JL, Jorizzo JL, SchafferJV, eds. Dermatology. Elsevier Saunders, New Haven, CT, 2012: 693–694.2 Rongioletti F. Cutaneous mucinoses. In: Griffiths C, Barker J, Bleiker T,Chalmers R, Creamer D, eds. Rook’s Textbook of Dermatology, 9th edn.Wiley Blackwell, Chichester, West Sussex, UK, 2016: 5311–5313.3 da Cunha Filho RR, de Almeida HL Jr, Brum EP, Lima MK, Marques eSilva R. Macular amyloidosis: a case report with scanning electron micro-scopy. J Eur Acad Dermatol Venereol 2016; 30: 889–90.4 Almeida HL Jr, Bicca EB, Breunig JA, Rocha NM, Silva RM. Scanningelectron microscopy of lichen sclerosus. An Bras Dermatol 2013; 88: 247–9.DOI: 10.1111/jdv.14006© 2016 European Academy of Dermatology and VenereologyJEADV 20162 Letter to the Editor

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Pretibial myxoedema: a case report with scanning electron microscopy.

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