Dermatology: Practical and Conceptual Letter | Dermatol Pract Concept 2019;9(3):18 235 Dermatology Practical & Conceptual Primary Localized Cutaneous Nodular Amyloidosis on a Toe: Clinical Presentation, Histopathology, and Dermoscopy Findings Isadora L.O. Ferreira1, Elizabeth L. Fernandes1, Jan Lapins2, Tatiane Benini1, Luciana C. Silva1, Marcia A. Lanzoni3, Denise Steiner1 1 Serviço de Dermatologia, Universidade de Mogi das Cruzes, São Paulo, Brazil 2 Department of Dermatology, Karolinska University Hospital, Stockholm, Sweden 3 Serviço de Patologia, Departamento de Medicina, Universidade de Taubaté, São Paulo, Brazil Key words: dermatology, amyloidosis, nodular amyloidosis, dermoscopy Citation: Ferreira ILO, Fernandes EL, Lapins J, Benini T, Silva LC, Lanzoni MA, Steiner D. Primary localized cutaneous nodular amyloidosis on a toe: clinical presentation, histopathology, and dermoscopy findings. Dermatol Pract Concept. 2019;9(3):235-236. DOI: https://doi.org/10.5826/dpc.0903a18 Accepted: March 19, 2019; Published: July 31, 2019 Copyright: ©2019 Ferreira et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: None. Competing interests: The authors have no conflicts of interest to disclose. Authorship: All authors have contributed significantly to this publication. Corresponding author: Isadora L.O. Ferreira, MD, Rua Dom Antonio Candido de Alvarenga 170, Mogi das Cruzes, São Paulo, Brazil, 08780-070. Email: isadora_lopes@hotmail.com Introduction Amyloidosis represents a group of diseases characterized by extracellular deposition of amyloid and is traditionally clas- sified as systemic or localized. Primary localized cutaneous nodular amyloidosis (PLCNA) is the rarest form of cutane- ous amyloidosis, usually occurring equally among genders. It manifests as single or multiple nodules or infiltrated plaques, usually localized on the face, particularly the nose, genitals, trunk, and limbs. Progression to systemic involvement is quite uncommon, occurring in approximately 7% of cases [1]. Case Presentation A 71-year-old-man from São Paulo, Brazil, with no comor- bidities, presented with a 5-year history of an asymptomatic single, soft, large, elongated pink nodule in the toe web along the fourth left toe (Figure 1, A and B). Polarized contact dermoscopy showed white shiny streaks on orange-pink background (Figure 1C). A local ultrasound examination revealed a hypoechoic tumor measuring 2.3 × 1.3 × 1.2 cm that extended to subcutaneous tissues. Differential diagnos- tic possibilities as acral manifestations of soft tissue tumors including superficial acral fibromyxoma, inclusion body fibromatosis, and acral fibrokeratoma were considered. Histopathology from a punch biopsy showed an epidermis with focal mild spongiosis, parakeratosis, and lymphocyte exocytosis together with a proliferation of desmoplastic spindle cells with a nonspecific lymphoplasmocytic inflam- matory process. Immunohistochemical examination was inconclu- sive. Histopathology from complete excision showed that throughout the dermis, there were nodular deposits of hyaline and eosinophilic material, with spindle-shaped cells (Figure 1D). Hyaline-like, eosinophilic material was also seen in the walls of small vessels and subcutaneous 236 Letter | Dermatol Pract Concept 2019;9(3):18 long-term follow-up study. Br J Dermatol. 2001;145(1):105-109. 2. Arnold SJ, Bowling JC. “Shiny white streaks” in lichen amyloidosis: a clue to diagnosis. Australas J Dermatol. 2012;53(4):272-273. 3. Rongioletti F, Atzori L, Ferreli C, et al. A unique dermoscopy pattern of primary cutaneous nodular amyloidosis mimick- ing a granulomatous disease. J Am Acad Dermatol. 2016;74(1):e9-e10. Dermoscopic findings of PLCNA have not been extensively described in the literature, and we suggest that polarized dermoscopy can be a comple- mentary and useful aid for noninvasive diagnosis. References 1. Woollons A, Black MM. Nodular local- ized primary cutaneous amyloidosis: a tissue. Congo red staining showed the presence of a brick-red deposit in the dermis (Figure 1E), which under polar- izing microscopy showed apple-green birefringence. The diagnosis of PLCNA was established based on clinical find- ings and histopathology in the absence of systemic manifestations of amyloi- dosis. Beside the lesion on the foot, the patient was asymptomatic. Complete blood cell count, B-glucose, electropho- resis, ANA test, urine test, and Bence Jones protein test results were normal. Abdominal ultrasound and chest X-ray showed nothing remarkable. No sys- temic manifestations of amyloidosis were identified. The patient is under- going 6-month follow-up intervals with clinical and laboratory examina- tions. After 1 year no recurrence was detected. Conclusions We describe a rare presentation of pri- mary cutaneous amyloidosis located on an uncommon body site. Polarized dermoscopy examination could have contributed to the clinical suspicion of the correct diagnosis in this case. Skin lesions with an altered composition or orientation of collagen will often reveal, under polarized dermoscopy, shiny white streaks [2]. In polarized dermoscopy of lichen amyloidosis, the deposition of amyloid substance with birefringent properties in the dermis is reported to be visualized as shiny white streaks [2]. A case report of dermos- copy of PLCNA described an orange hue, otherwise seen in dermal granu- lomatous skin disorders, as a clue for diagnosis [3]. The dermoscopic pattern of polarization-specific white structures in a background of orange-pink color, present in our case, could be an addi- tional feature that can contribute to the PLCNA diagnosis. Figure 1. (A, B) Clinical presentation of a single, soft, pink nodule on the fourth left toe. (C) Polarized contact dermoscopy of the lesion showing birefringent properties present as shiny white structures on orange-pink background. (D) Histopathological examination of the le- sion shows hyaline eosinophilic nodular deposits, with spindle-shaped cells throughout the dermis. (E) Histopathological characteristics of the lesion, using Congo red staining evidenc- ing presence of a brick-red deposit in the dermis. [Copyright: ©2019 Ferreira et al.] A C D E B