Ann Dermatol.  2019 Dec;31(6):662-665. 10.5021/ad.2019.31.6.662.

Hair Follicle Nevus Located on the Neck: Comparison with Accessory Tragus, Cervical Chondrocutaneous Branchial Remnants and Trichofolliculoma

• Lee JS
• Yang JH
• Park H
• Yoon HS
• Cho S

• KMID: 2461989
• DOI: http://doi.org/10.5021/ad.2019.31.6.662

Abstract

Hair follicle nevus (HFN) is a rare, benign, follicular hamartoma that most frequently presents as a congenital nodule on the face. We experienced a rare case of HFN on the neck of a 14-year-old boy and performed a pilot immunohistochemical study with cytokeratin 19 (CK19) to compare the staining pattern of hair follicles in HFN and its differential diagnoses, accessory tragus, cervical chondrocutaneous branchial remnants (CCBR) and trichofolliculoma. With hematoxylin and eosin stain, HFN showed numerous tiny hair follicles in the dermis with several sebaceous and eccrine glands, and perifollicular fibrous thickening. With CK19 stain, some hair follicles in HFN and CCBR showed positive expression, a few hair follicles in accessory tragus showed weak expression, and no hair follicles in trichofolliculoma showed expression. The present report supports the view that HFN, accessory tragus and CCBR are within the same spectrum of hamartomas.

Keyword

Accessory tragus; Cervical chondrocutaneous branchial remnants; Cytokeratin 19; Hair follicle nevus; Trichofolliculoma

MeSH Terms

Adolescent
Dermis
Diagnosis, Differential
Eccrine Glands
Eosine Yellowish-(YS)
Hair Follicle*
Hair*
Hamartoma
Hematoxylin
Humans
Keratin-19
Male
Neck*
Nevus*
Eosine Yellowish-(YS)
Hematoxylin
Keratin-19

Figure

• 

  Fig. 1 Two separate papules on the right neck. (A) Asymptomatic and soft pedunculated skin-colored papule on the right lower neck and red-colored papule with bleeding tendency on the right upper neck. (B) Closer view of the lower flesh-colored lesion.

• 

  Fig. 2 Histopathology of the lower skin-colored papule. (A) Numerous vellus hair follicles are located in the dermis, and several sebaceous and eccrine glands are connected to the hair follicles (H&E, ×40). (B) Perifollicular stroma shows fibrous thickening (H&E, ×200).

• 

  Fig. 3 Cytokeratin 19 (CK19) expression in the hair follicles in hair follicle nevus (HFN) (14-year-old), accessory tragus (8-year-old), cervical chondrocutaneous branchial remnants (CCBR) (24-month-old), and trichofolliculoma (37-year-old) (upper right insets, clinical pictures; lower right insets, hematoxylin and eosin-stained pictures in 40 fold magnification). (A, B) Some hair follicles in HFN and CCBR showed positive expression of CK19 (CK19, ×100). (C) Few hair follicles in accessory tragus showed weak expression of CK19 (triangles) (CK19, ×100). (D) Hair follicles in trichofolliculoma showed no expression of CK19 (CK19, ×100).

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