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American Journal of Dermatopathology:
doi: 10.1097/DAD.0b013e31824d4f86
Letters to the Editor

The Melanocytic Epithelioid Cell Nevus of the Thigh of Woman: A Simulator of Melanoma

Donati, Pietro MD; Muscardin, Luca MD; Cota, Carlo MD; Panetta, Chiara MD; Paolino, Giovanni MD

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San Gallicano Dermatological Institute, Istituto di Ricovero e Cura a Carattere Scientifico Rome, Italy

The authors declare no funding or conflicts of interest.

To the Editor:

We have read with much interest the article of Coras et al1 and the abstract of Buonaccorsi et al,2 presented at the 14th Joint Meeting of the International Society of Dermatopathology (February 2–3, 2011, New Orleans, LA). For this reason, we would like to submit our observation about similar histopathological features of melanocytic proliferation on the thighs of women that can place diagnostic challenges.

We have observed a group of 27 patients in our institute from November 2006 to February 2009, mostly women (female-male ratio = 25:2; mean age, 35.6 years; median age, 37 years; range, 24–51 years), each with a small melanocytic lesion, typically located on the thigh (Fig. 1). The lesions were solitary, generally symmetric, flat, 4 to 5 mm in diameter, brown to pink colored, with regular margin, always located on the thighs. Patients reported new or doubtful onset. Two thirds of the lesions were examined by dermatoscopy.

Figure 1
Figure 1
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Histologically, all lesions showed a small, relatively, intraepidermal proliferation of melanocytes that are often drop shaped, with a pale nucleus and an abundant, clear cytoplasm, with an epithelioid or pseudo-pagetoid appearance (Figs. 2, 3). Melanocytes are arranged almost in solitary units scattered in the lower portion of the epidermis and absent in the outermost malpighian layer and stratum corneum. In 2 cases, melanocytes were arranged in small nests, located only at the dermoepidermal junction. None of these cases showed epidermal hyperplasia, hypergranulosis, or hyperkeratosis. Apoptotic cells in the epidermis were observed in 12 cases, while 10 cases showed an hyperpigmentation of the basal keratinocytes. A superficial perivascular lymphocytic infiltrate was present in 6 cases; 4 cases presented also melanophages in the papillary dermis without fibrosis.

Figure 2
Figure 2
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Figure 3
Figure 3
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Based on the clinico-dermatoscopicaland histopathological aspects, we propose the term “epithelioid cell melanocytic nevus” of the thigh, for this particular type of melanocytic lesion that can mimics a melanoma in situ.

We think that pathologists should be familiar with this particular type of nevus, and in accordance with the colleagues, we can consider the thigh of women as another special site for peculiar clinicopathological features of nevi.3

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REFERENCES

1. Coras B, Landtharer M, Stolz W, et al.. Dysplastic melanocytic nevi of the lower leg: sex-and site-specific histopathology. Am J Dermatopathol. 2010;32:599–602.

2. Buonaccorsi JN, Suster S, Plaz JA. Potential misdiagnosis of atypical benign melanocytic lesion of the thigh: a clinicopathological study of 41 cases. Am J Dermatopathol. 2011;33:422.

3. Hosler GA, Moresi GM, Barret TL. Nevi with site-related atypia: a review of melanocytic nevi with atypical histologic features based on anatomic site. J Cutan Pathol. 2008;35:889–898.

© 2012 Lippincott Williams & Wilkins, Inc.

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