Importance of keen observation for the diagnosis of epidermal cysts: Dermoscopy can be a useful adjuvant tool
Authors: Je-Ho Mun, Sung-Min Park, Tae-Wook Kim, Byung-Soo Kim, Hyun-Chang Ko, Moon-Bum Kim
Journal: Journal of the American Academy of Dermatology (2014)

To the Editor: Although epidermal cysts are the most common cutaneous cysts and frequently encountered in daily dermatologic practice, differential diagnosis of them is very broad and is often a diagnostic challenge.1Garcia-Zuazaga J. Ke M.S. Willen M. Epidermoid cyst mimicry: report of seven cases and review of the literature.J Clin Aesthet Dermatol. 2009; 2: 28-33PubMed Google Scholar A characteristic of epidermal cysts is a clinically visible punctum representing the orifice of an obstructed hair follicle from which the cyst originates. In case punctum is not visible, diagnosing epidermal cysts can be difficult. Here, we report 3 cases in which dermoscopy helped in diagnosing epidermal cysts by enabling visualization of small puncta that were hardly detected under naked-eye examination. A 34-year-old man presented with a soft mass on the occipital scalp. He first noticed the mass 6 years earlier, and it slowly enlarged. He reported no symptom, smell, or discharge from the mass. Our clinical differential diagnosis included lipoma, or epidermal, dermoid, pilar, or other cysts or tumors. On clinical examination, the overlying skin appeared normal (Fig 1, A and B). However, dermoscopic examination showed a punctum barely visible to the naked eye (Fig 1, C). Subsequently, we successfully enucleated the cyst via a small elliptical incision. The histology of the cyst is shown in Fig 1, D. A 2-year-old girl presented with an asymptomatic nodule on the concha of her right ear (Fig 2, A and C). The movable and nontender nodule was noticed 2 months previously. The initial clinical differential diagnosis included lipoma, neurofibroma, or epidermal or dermoid cysts. Subsequent dermoscopic examination of the nodule showed a punctum hardly visible under naked-eye examination (Fig 2, E). The histopathology of the excised cyst was consistent with that of an epidermal cyst. A 39-year-old man presented with 10-year history of an asymptomatic mass on the back of his neck (Fig 2, B and D). As in the first patient, a punctum was hardly visible under naked-eye examination. However, under dermoscopic evaluation, a punctum was observed (Fig 2, F). We successfully performed surgery with minimal incision, and extracted the cyst. The histopathology of the cyst was consistent with that of an epidermal cyst. The diagnostic application of dermoscopy is increasing in general dermatology and for skin tumors because it enables clinicians to visualize morphologic structures that are often invisible to the naked eye.2Micali G. Lacarrubba F. Massimino D. Schwartz R.A. Dermatoscopy: alternative uses in daily clinical practice.J Am Acad Dermatol. 2011; 64: 1135-1146Abstract Full Text Full Text PDF PubMed Scopus (155) Google Scholar, 3Zalaudek I. Lallas A. Moscarella E. Longo C. Soyer H.P. Argenziano G. The dermatologist's stethoscope–traditional and new applications of dermoscopy.Dermatol Pract Concept. 2013; 3: 67-71PubMed Google Scholar Based on our experience, we suggest that dermoscopy can be used as a helpful tool for diagnosing epidermal cysts. Dermoscopic examination may help visualize the punctum and increase the diagnostic accuracy in a proportion of epidermal cysts with very small puncta. In our cases, the puncta were barely detectible on direct visual observation. As shown in Fig 1, D, the punctum was about 0.5 mm, which can be difficult to observe under naked-eye examination. To our knowledge, this is the first report of epidermal cysts in which puncta were barely visible to the naked eye; however, dermoscopic examination led to the correct diagnosis by enabling the visualization of the puncta. If the diagnosis of epidermal cyst can be made before surgery, a better treatment option such as surgery with minimal incision and cyst extraction can be chosen; this will produce better cosmetic results.4Yang H.J. Yang K.C. A new method for facial epidermoid cyst removal with minimal incision.J Eur Acad Dermatol Venereol. 2009; 23: 887-890Crossref PubMed Scopus (29) Google Scholar