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F-FDG PET/CT Findings in a Patient With a Proliferating Trichilemmal Cyst Pierre Leyendecker, MD,* Ghislaine de Cambourg, MD,† Antoine Mahé, MD,† Alessio Imperiale, MD, PhD,*‡§ and Cyrille Blondet, MD*‡§||

Abstract: Proliferating trichilemmal cyst is considered as a rare tumor that originates in the outer root sheath of hair follicle. Metastatic potential has not been yet fully established. Moreover, histological analysis does not allow precise malignancy prediction. Proliferating trichilemmal cyst glucose metabolism behavior was never previously described. Herein, we report the case of a 62-year-old patient with a left shoulder proliferating trichilemmal cyst showing an intense uptake of 18F-FDG on PET/CT examination. 18F-FDG PET/CT could be proposed to optimize diagnostic strategy of patients with proliferating trichilemmal cysts. Key Words: F-18 FDG, PET/CT, proliferating trichilemmal cyst, proliferating trichilemmal tumor, malignant proliferating trichilemmal tumor (Clin Nucl Med 2015;40: 598–599)

Received for publication November 20, 2014; revision accepted January 8, 2015. From the *Service de Biophysique et de Médecine Nucléaire, Hôpitaux Universitaires de Strasbourg, Strasbourg, France; †Service de Dermatologie, Hôpital Pasteur, Hôpitaux Civils de Colmar, Colmar, France; ‡ICube, Université de Strasbourg/ CNRS UMR 7357, Strasbourg, France; §Fédération de Médecine Translationnelle de Strasbourg (FMTS), Faculté de Médecine, Strasbourg, France; and ||Service de Médecine Nucléaire, Clinique du Diaconat, Mulhouse, France. Conflicts of interest and sources of funding: none declared. Reprints: Cyrille Blondet, MD, Service de Biophysique et de Médecine Nucléaire Nouvel Hôpital Civil 1, Place de l'Hôpital 67091 Strasbourg Cedex, France. E-mail: [email protected]. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0363-9762/15/4007–0598

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REFERENCES 1. Park BS, Yang SG, Cho KH. Malignant proliferating trichilemmal tumor showing distant metastases. Am J Dermatopathol. 1997;19:536–539. 2. Aneiros-Fernandez J, Jimenez-Rodriguez JM, Martin A, et al. Giant proliferating trichilemmal malignant tumor. Indian J Dermatol Venereol Leprol. 2011;77:730. 3. Folpe AL, Reisenauer AK, Mentzel T, et al. Proliferating trichilemmal tumors: clinicopathologic evaluation is a guide to biologic behavior. J Cutan Pathol. 2003;30: 492–498. 4. Noto G, Pravata G, Arico M. Malignant proliferating trichilemmal tumor. Am J Dermatopathol. 1997;19:202–204. 5. Herrero J, Monteagudo C, Ruiz A, et al. Malignant proliferating trichilemmal tumours: a histopathological and immunohistochemical study of three cases with DNA ploidy and morphometric evaluation. Histopathology. 1998;33:542–546. 6. Kim HJ, Kim TS, Lee KH, et al. Proliferating trichilemmal tumors: CT and MR imaging findings in two cases, one with malignant transformation. Am J Neuroradiol. 2001;22:180–183. 7. Jung J, Cho SB, Yun M, et al. Metastatic malignant proliferating trichilemmal tumor detected by positron emission tomography. Dermatol Surg. 2003;29:872–874. 8. Hong IK, Kim DY. F-18 FDG PET/CT of a uterine smooth-muscle tumor of unknown malignant potential. Clin Nucl Med. 2011;36:934–936.

Clinical Nuclear Medicine • Volume 40, Number 7, July 2015 Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.

Clinical Nuclear Medicine • Volume 40, Number 7, July 2015

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F-FDG PET/CT Findings of Trichilemmal Cyst

FIGURE 1. Physical examination revealed an exophytic tumor, well circumscribed on the posterior face of the left shoulder (A); histological analysis assessed a proliferating trichilemmal cyst. Multiplanar reconstructions showing intense areas of 18F-FDG uptake in the left shoulder proliferating trichilemmal cyst (B), in multiple enlarged left axillary lymph nodes (C) and in a left breast nodule (D). We illustrate the results of 18F-FDG PET/CT in a 62-year-old woman addressed to our institution for morphofunctional characterization of a tissular lesion in the dorsal face of the left shoulder. It appeared clinically as a subcutaneous exophytic mass of approximately 10-cm diameter, firm and mobile, with several central ulcerations, associated with multiple enlarged palpable left axillary lymph nodes. Histologic examination of the tumor revealed a proliferating trichilemmal cyst, also referred as proliferating trichilemmal tumor. A whole-body 18F-FDG PET/CT examination was carried out in our patient to characterize the axillary lymph nodes and the metabolic behavior of the shoulder-proliferating trichilemmal cyst. PET/CT showed an intense uptake (SUVmax = 19) in the cutaneous tumor (arrow) and in the multiple enlarged left axillary lymph nodes (arrowhead, Fig. C). Unexpectedly, an intense increased 18F-FDG uptake (SUVmax = 11) was also observed in a left breast nodule (arrowhead, Fig. D). Herein, our case appeared as a diagnostic challenge, whether the axillary lymph nodes have to be considered as an extension of the proliferating trichilemmal cyst, whether as metastatic localizations of a synchronous primary breast cancer. Finally, histopathologic examination showed an infiltrative left breast ductal carcinoma with homolateral lymph node extension. Proliferating trichilemmal cyst is a proliferating cutaneous epithelial cyst differentiating toward the isthmic portion of the outer root sheath of hair follicle, usually described as a benign tumor, which occurs most commonly on the scalp of elderly women.1 However, according to histological analysis, there are less than 30 published cases of malignant proliferating trichilemmal cysts, classified as low-grade or high-grade malignant tumors.2 Moreover, metastases may be noticed at the time of diagnosis or until 30 years later3 and even cases of benign-looking proliferating trichilemmal cysts without cytologic or architectural atypia were associated to systemic metastatic spread and death.4 Cellular atypia, chromosomal ploidy, and morphometric analysis are not reliable markers of metastatic potential.5 Therefore, contrast-enhanced CT and MRI could seem useful to assess potential infiltration of the surrounding soft tissues.6 To our knowledge, there are extremely limited data about the role of 18 F-FDG PET/CT for the management of proliferating trichilemmal cysts. Only one patient was previously explored with 18F-FDG PET/CT to assess lymph node metastases after having surgically removed a recurrent scalp lesion.7 In conclusion, this case shows proliferating trichilemmal cyst intense glucose avidity, suggesting 18F-FDG PET/CT value for the workup of these tumors, where malignant potential is not definitely assessed.8

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599

CT Findings in a Patient With a Proliferating Trichilemmal Cyst.

Proliferating trichilemmal cyst is considered as a rare tumor that originates in the outer root sheath of hair follicle. Metastatic potential has not ...
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