• Korean Journal of Head & Neck Oncology
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• v.22 no.1
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• pp.55-57
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• 2006

Pilomatrixoma is an unusual benign cutaneous tumor, originating from precursor cells that normally differentiate into hair matrix cells. The majority of pilomatrixoma is seen in the first two decades of life, and they are extremely rare in older patients. Thus, pilomatrixoma is often not considered in the clinical differential diagnosis of solitary, firm nodules in older adults. Most present as firm, solid nodules in the head and neck region. We present two cases of a non-calcifying pilomatrixoma in older patients. One lesion arose from the upper neck in 54 year-old male and the other from the cavum concha of left ear in 35 year-old male.

• Archives of Plastic Surgery
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• v.33 no.6
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• pp.753-756
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• 2006

Purpose: Pilomatrixoma is a benign, usually asymptomatic tumor. It presents clinically as a solitary superficial subcutaneous nodule measuring between 0.5 cm and 5 cm in diameter on the head or upper extremeties and has not been reported after skin graft. The objective of this article is to report our experience in treating pilomatrixoma which occurred after split thickness skin graft on the lower extremity. Methods: A 56-year-old female was treated in August 2005 with a $0.5{\times}0.5cm$ firm subcutaneous nodule at recipient site of split thickness skin graft on the left medial thigh. The tumor was successfully removed by complete excision and histologic examination was followed. Results: The diagnosis was pilomatrixoma which was characterized by a dual population of proliferating basophilic cells and diagnostic shadow cells. Conclusion: The tumor was successfully treated by complete resection. The authors report this very rare case of pilomatrixoma which occurred at recipient site of split thickness skin graft.

• The Korean Journal of Cytopathology
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• v.10 no.1
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• pp.91-96
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• 1999

Sometimes a pilomatrixoma on upper neck can be misdiagnosed as primary salivary gland tumor, skin adnexal tumor or metastatic carcinoma. On fine needle aspiration cytology(FNAC), characteristic features are ghost cells, basaloid cells, and calcium deposits, among which presence of ghost cells seems to be the key to recognize it. Here we present a cytologically misdiagnosed case of pilomatrixoma. A 32-year-old man presented a subcutaneous mass on the right posterior neck. It has grown slowly for 1 year, and was nontender, well circumscribed, hard, and movable mass. An Initial FNAC yielded only monomorphic population of highly mitotic basaloid cells, without anucleated ghost cells, chronic inflammatory cells or foreign-body giant cells, suggestive of a poorly differentiated carcinoma. However, that was inconsistent with patient's clinical findings. For further correct diagnosis, FNAC was repeated, which yielded the basaloid cells and foreign-body giant cells. The diagnosis of pilomatrixoma could be made and the mass was excised. This case demonstrates that the pilomatrixoma should be considered in the differential diagnosis of subcutaneous aspirates containing not ghost cells but a dominant population of basaloid cells.

• The Korean Journal of Cytopathology
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• v.11 no.1
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• pp.53-58
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• 2000

Pilomatrixoma is a benign tumor which usually occur as a solitary, firm nodule in the head and neck, and upper extremities of young people. This tumor is occasionally encountered during aspiration biopsy of subcutaneous masses, but only a small number of cases are correctly diagnosed prior to excision. We report five cases of pilomatrixoma. Four cases occurred in the neck and one case in the back. The characteristic fine needle aspiration cytologic features are shadow cells and basaloid cells in the background of inflammatory cells, including some multinucleated giant cells. The shadow cells were recognized in all five cases. These cells were pale, anucleated cells with relatively distinct cell borders. $May-Gr\ddot{u}nbald-Giemsa$ stain is useful for the identification of shadow cells. The recognition of shadow cells appears to be essential for accurate diagnosis of pilomatrixoma.

• The Korean Journal of Cytopathology
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• v.8 no.2
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• pp.155-159
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• 1997

Pilomatrixoma is a benign skin appendage tumor of hair matrix cell origin. The cytological appearance of this tumor may cause problems when attempting to establish a differential diagnosis with other neoplasms. Herein we report the aspiration cytology findings of two cases of pilomatrixoma. One case was diagnosed as atypical cell clusters initially and the other was diagnosed as pilomatrixoma. On cytologic examination, both cases showed clusters of tightly arranged basaloid cells with an uniform appearance, scanty cytoplasm and round hyperchromatic nuclei. There were histiocytes and multinucleated foreign body giant cells merged with the amorphous opaque orangeophilic materials of "ghost cells". The differential diagnosis with other neoplasms is discussed.

• Archives of Craniofacial Surgery
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• v.21 no.5
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• pp.288-293
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• 2020

Background: Pilomatrixoma is a benign tumor that originates from the hair follicle matrix. It usually presents as a hard, slow growing, solitary mass that can be easily misdiagnosed as other skin masses. The aim of this study was to clinically analyze a case series of pilomatrixoma in pediatric patients from Korea. Methods: A total of 165 pediatric patients from 2011 to 2018 with a histological diagnosis of pilomatrixoma were included. A retrospective review was performed using the electronic medical records, including patient demographics, number and location of the mass, clinical and imaging presentation, and postoperative outcomes. Results: There were 61 male and 104 female patients with 152 solitary and 13 multiple pilomatrixomas. Among solitary pilomatrixomas, the lesion commonly occurred in the head and neck (84.2%), followed by upper limbs (11.2%), lower limbs (3.3%), and trunk (1.3%). The pilomatrixoma lesion presented as the following types based on our clinical classification: mass (56.02%), pigmentation (25.31%), mixed (12.65%), ulceration (4.82%), and keloid-like (1.2%). Ultrasonography showed a high positive predictive value (95.56%). There were no specific complications observed except for two cases of recurrence. Conclusion: Pilomatrixoma has various clinical feature presentations and commonly occurs in the head and neck. Ultrasonography is a helpful diagnostic tool. Surgical removal of the lesion is the main treatment method with a low recurrence rate.

• The Korean Journal of Cytopathology
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• v.4 no.1
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• pp.25-29
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• 1993

We describe cytologic findings of two cases of pilomatrixoma which had been cytologically misdiagnosed as suspicious malignant and malignant lesions in 35 year-old and 22 year-old females who presented a palpable neck mass. The cytologic smears showed many basaloid cells with a high nuclear-cytoplasmic ratio, nuclear hyperchromatism and prominent nucleoli, keratinized squamous cells with pyknotic nuclei, foreign body giant cells, and chronic inflammatory cells in necrotic back-ground. Retrospective view of this aspiration smear revealed that these findings were characteristic features of pilomatrixoma, and the evenly distributed chromatin pattern as well as the lack of nuclear pleomorphism were considered to be the differential points from malignant neoplasm. Pilomatrixoma is a benign neoplasm which should be included in differential diagnosis if the fine needle aspiration cytologic smear of a neck mass or subcutaneous mass of any site showed these features.

• Imaging Science in Dentistry
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• v.33 no.4
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• pp.231-234
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• 2003

We report a case of pilomatrixoma presenting in the right cheek of a 6-year-old girl. In the panoramic view, a small, ovoid-shaped, and nonhomogenous calcified mass was superimposed on the right mandibular angle, The mass was located on the skin overlying the right mandibular ramus area in the skull P-A view. The tumor had a strongly reflective pattern with acoustic shadowing in sonographic view. We also illustrate how these lesions can be effectively diagnosed.

• Korean Journal of Head & Neck Oncology
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• v.22 no.2
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• pp.147-150
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• 2006

Pilomatrixoma is an uncommon tumor arising from hair follicles. Commonly occur in children and most frequently in the head and neck region. It can be mistaken for parotid gland tumor, dermoid cyst, or epidermoid cyst, especially when large lesions develop over the periauricular area, difficulty discerning them from lesion developing within the superficial lobe of the parotid gland may occur. We experienced two cases of pilomatrixomas mimicking parotid gland tumor. Although their histologic appearance is characteristic, they may be clinically misdiagnosed. However, combining clinical information with the distinct histologic features should lead to the correct diagnosis.

• Proceedings of the Korean Society of Veterinary Pathology Conference
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• 2005.11a
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• pp.103-103.1
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• 2005