Dermatology: Practical and Conceptual 120 Observation | Dermatol Pract Concept 2018;8(2):9 DERMATOLOGY PRACTICAL & CONCEPTUAL www.derm101.com Case Presentation A 44-year-old fair-skinned male presented with a several-year history of a slowly enlarging asymptomatic nodule on his right forearm. He had an extensive sun exposure history and prior history of basal cell carcinomas but was otherwise in good general health. There was no family history of cancer. The physical examination revealed a 1 x 1 cm solid, well- circumscribed, white, firm nodule on the extensor aspect of his right forearm (Figure 1). Dermoscopy showed a homogeneous white background with some peripheral arborizing vessels and mild erythema- tous halo (Figure 2). A complete excisional biopsy was per- formed. Histology revealed a well-circumscribed polypoid lesion covered by an atrophic epidermis. The dermis con- tained sclerotic bundles of collagen with a storiform pattern and scattered fibroblasts; no collagen bundles with plywood- like or concentrically lamellar pattern were identified. No depressed surface, dermal atrophy, infiltrative edges, vascular proliferation, dermal spindle-shaped or dendritic melanocytes were seen (Figure 3). Diagnosis Solitary storiform collagenoma (sclerotic fibroma) Discussion The solitary storiform collagenoma (sclerotic fibroma) is a rare benign soft tissue tumor presenting as a slowly enlarging well-circumscribed solid, fibrous, pink, white or flesh-colored papule or nodule in young and middle-aged adults of both sexes [1]. It is more commonly found on the face and limbs but has also been described on the scalp, trunk, oral mucosa and nail bed [2]. The presence of multiple storiform col- lagenomas is considered as a cutaneous marker of Cowden syndrome [3]. Histology of sclerotic fibromas reveals a well- circumscribed non-encapsulated dermal nodule with hypocel- lular storiform collagen bundles showing prominent clefts [4], sometimes with accumulation of collagen bundles in biphasic growth and arranged in a plywood-like or concentrically lamellar patterns [5]. Dermoscopy of a solitary storiform collagenoma Mona Ebadian1, Luigi Citarella1, Damian Collins1, Salvador Diaz-Cano2, Lucia Pozo-Garcia1 1 Lewisham and Greenwich NHS Trust, London, UK 2 Kings College Hospital, London, UK Key words: collagenoma, storiform collagenoma, sclerotic fibroma, Cowden syndrome Citation: Ebadian M, Citarella L, Collins D, Diaz-Cano S, Pozo-Garcia L. Dermoscopy of a solitary storiform collagenoma. Dermatol Pract Concept. 2018;8(2):120-122. DOI: https://doi.org/10.5826/dpc.0802a09 Received: January 16, 2018; Accepted: February 20, 2018; Published: April 30, 2018 Copyright: ©2018 Ebadian 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. All authors have contributed significantly to this publication. Corresponding author: Lucia Pozo-Garcia, MD, PhD, Lewisham and Greenwich NHS Trust, Stadium Road, London, Greater London, SE18 4QH, United Kingdom. Tel. +44 20 88365261 Fax. +44 20 88366935. Email:  lpozo@doctors.org.uk The dermoscopic features of solitary storiform collagenomas (sclerotic fibromas) have not been de- scribed previously, as these are rare cutaneous soft tissue tumors. The presence of multiple lesions is considered a marker of Cowden syndrome. They can also present as single firm cutaneous nodules. We present an unusual single nodule with distinct dermoscopic and histologic features. ABSTRACT Observation | Dermatol Pract Concept 2018;8(2):9 121 with peripheral arborizing vessels; this pattern has not been described previously. Some atypical forms of dermatofibro- mas [6], late stages of sclerotic dermatofibromas and amela- notic blue nevi, may occasionally present with similar dermo- scopic features [7]. A sclerotic fibroma-like dermatofibroma has also been described as an uncommon variant of dermato- fibroma [8]. It is unclear if storiform collagenomas represent We present an unusual solid, single nodule in a fair- skinned patient with prior history of basal cell carcinomas. Dermoscopy showed a homogeneous white background Figure 1. Well-circumscribed, white, firm nodule with erythematous halo and superficial vascularization. [Copyright: ©2018  Ebadian et al.] Figure 2. Dermoscopy shows a homogeneous structureless white le- sion with erythema and arborizing vessels in peripheral distribution (polarized contact dermoscopy, x10). [Copyright: ©2018  Ebadian et al.] Figure 3. Well-circumscribed polypoid lesion contained collagen bundles separated by prominent clefts with scattered fibroblasts. Hematox- ylin-eosin stained sections (A. 40x, B. 100x, C. 200x). [Copyright: ©2018 Ebadian et al.] 122 Observation | Dermatol Pract Concept 2018;8(2):9 4. Lo WL, Wong CK. Solitary sclerotic fibroma. J Cutan Pathol. 1990 Oct;17(5):269-273. 5. Nakashima K, Yamada N, Adachi K, Yoshida Y, Yamamoto O. Soli- tary sclerotic fibroma of the skin: morphological characterization of the ‘plywood-like pattern’. J Cutan Pathol. 2008 Oct;35 Sup- pl 1:74-79. 6. Coelho de Sousa V, André Oliveira A. Nodular lesion with polymor- phous vascular pattern. Dermatol Pract Concept. 2017;7(4):81-83. 7. Ma C, Chambers CJ, Kiuru M, Marsee DK, Silverstein M. Amela- notic blue nevus. JAAD Case Rep. 2017 Mar;3(2):93-94. 8. Gonzalez-Vela MC, Val-Bernal JF, Martino M, Gonzalez-Lopez MA, Garcia-Alberdi E, Hermana S. Sclerotic fibroma-like derma- tofibroma: an uncommon distinctive variant of dermatofibroma. Histol Histopathol. 2005 Jul;20(3):801-806. 9. Donati P, Amantea A, Carducci M, Balus L. Sclerotic (hypocellular) fibromas of the skin. Br J Dermatol. 1991 Apr;124(4):395-396. a fibrous tissue hamartoma or a genuinely fibrohistyocitic neoplasm; some storiform collagenomas may correspond to involuting dermatofibromas [9]. Storiform collagenomas should be considered in the differential diagnosis of acquired white firm papules or nodules. Histology is needed to confirm the diagnosis. References 1. Metcalf JS, Maize JC, LeBoit PE. Circumscribed storiform collagenoma (sclerosing fibroma). Am J Dermatopathol. 1991 Apr;13(2):122-129. 2. Tosti A, Cameli N, Peluso AM, Fanti PA, Peserico A. Storiform collagenoma of the nail. Cutis. 1999 Sep;64(3):203-204. 3. Al-Daraji WI, Ramsay HM, Ali RB. Storiform collagenoma as a clue for Cowden disease or PTEN hamartoma tumour syndrome. J Clin Pathol. 2007 Jul;60(7):840-842.