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Coccygeal Polypoid Eccrine Nevus.

Although prevalent in adults and associated with obesity and aging, skin tags are rare in children and may warrant further evaluation. In children, the most-common locations for skin tags are the preauricular region and the vaginal region. Preauricular skin tags occur in 5 to 10 patients per 1000 live births. They may be associated with hearing impairment in neonates, and thus neonates with preauricular skin tags should be screened for hearing loss. (1) Vaginal skin tags usually regress within a few weeks. (2) Children with coccygeal skin tags often warrant concern because occult spinal dysraphism may be suspected; in addition to skin tags, sacral hemangiomas, dimples, or clusters of hair may also overlie a spinal malformation. (3) Although present in the coccygeal region, coccygeal polypoid eccrine nevi, hamartomas with increased number or size of eccrine glands with no vascular proliferation, are not known to be associated with spinal dysraphism.

CLINICAL FEATURES

About 20 cases of eccrine nevi have been reported in the English-language medical literature, (4) with various clinical manifestations. Most eccrine nevi are associated with localized hyperhidrosis, but asymptomatic lesions have also been reported. There is no predominance in gender distribution, and eccrine nevi are uncommon at birth. (4) They are not associated with cutaneous or internal malformations. The unusual location of the coccygeal eccrine nevus as a flesh-colored papule on the midline of the coccyx (Figure 1) has been reported in 5 cases (Table 1). All but one of those lesions occurred in young girls and were present at birth. In addition, none of the reported cases was associated with internal malformation, except one with imperforate anus and unilateral multicystic kidney dysplasia.

HISTOPATHOLOGIC FINDINGS

Hematoxylin-eosin-stained sections demonstrate a polypoid fragment of skin with a slightly acanthotic epidermis with overlying hyperkeratosis (Figure 2, A). That finding may be attributed to the coccygeal location, in which frictional microtrauma occurs frequently. Within the reticular dermis, collections of well-formed eccrine ducts and glands are present. The dermal vascularity is within reference range in distribution, with no angiomatous components surrounding the eccrine units (Figure 2, B).

DIFFERENTIAL DIAGNOSIS

Table 2 summarizes the differential diagnoses. Coccygeal polypoid eccrine nevi should be distinguished from other eccrine nevi. An eccrine nevus is a hamartoma characterized by an increase in the number or size of eccrine glands. Eccrine nevi are localized hyperhidrosis not associated with other skin abnormalities. (5) Eccrine nevi are usually noted during childhood but are uncommon at birth. Eccrine nevi are common on upper extremities. Eccrine angiomatous hamartomas occur predominantly on the lower extremities as a pink-red patch or thin plaque, from 1 to 10 cm in diameter. (6) They may be associated with pain, hypertrichosis, itching, and hyperhidrosis. (7) Microscopically, the eccrine angiomatous hamartoma is composed of prominent capillary proliferations accompanied with eccrine units.

A hair follicle nevus is a congenital nodule made up of well-formed vellus hair follicles. (8) They are relatively rare, benign, congenital lesions and are most frequently found on the face and neck.

Skin tags are generally polypoid, with a flattened epidermis overlying loose collagen bundles and an absence of adnexal structures. Vulvar skin tags, which can be seen early in life, are similarly polypoid with a connective tissue core, but there may be a few sebaceous glands attached to the epidermal surface. Eccrine units are not prominent.

The adnexal polyp of neonatal skin presents as a small congenital polypoid lesion and typically is solitary. It is skin colored and regresses spontaneously within a few days of birth. It most commonly affects the areola of the breast, but other sites such as the scrotum and labia majora have been described. (9) Pathologically, the polyp core generally includes eccrine units as well as other structures including hair follicles and sebaceous glands.

Coccygeal polypoid eccrine nevi can also be distinguished from other sacrococcygeal lesions in the pediatric age group, such as teratoma, sacrococcygeal eversion, and tailgut cysts. In pediatric patients, teratomas, a form of dermoid cyst, are the most common presacral lesion. (10) Teratomas are mostly benign and are identified as palpable presacral or pelvic masses upon rectal examination and may extend into the abdomen. Most sacrococcygeal teratomas are seen after birth and are diagnosed before the age of 6 months.

Sacrococcygeal eversion is a condition in which the distal sacral and coccygeal vertebrae are curved in a retroverted direction. (11) This malformation results in a tail-like protrusion that is identified by varied histologic markers, including fatty tissue, nerve fibers, striated muscle fibers, and/or cartilage. Finally, tailgut cysts are congenital malformations in the presacral space and are a malformed remnant of the hindgut. (12) Tailgut cysts predominantly affect women, and while they can present in patients of any age, they usually appear between the ages of 30 and 60. Tailgut cysts can be asymptomatic or cause additional complications, such as a prolapsing anal cyst, infection, or organ compression, leading to digestive or urinary dysfunction. Although the lining of tailgut cysts can include different epithelium types, including columnar, transitional, or squamous tissues, glandular or transitional epithelium differentiate tailgut cysts from epidermoid and dermoid cysts.

CONCLUSIONS

Coccygeal polypoid eccrine nevus is a benign unique eccrine nevus located in the coccygeal area, characterized histopathologically by normal or hyperplastic eccrine glands surrounded by normal fibroadipose tissue with occasional overlying acanthotic and hyperkeratotic epidermis. Because so few cases have been reported, the inheritance pattern is unknown, and most cases are not associated with other internal defects.

References

(1.) Roth DA, Hildesheimer M, Bardenstein S, et al. Preauricular skin tags and ear pits are associated with permanent hearing impairment in newborns. Pediatrics. 2008;122(4):884-890.

(2.) Ainsworth S. Avery's diseases of the newborn, 8th ed [book review]. Arch Dis Child Fetal Neonatal Ed. 2005;90(4):F350.

(3.) Kriss VM, Desai NS. Occult spinal dysraphism in neonates: assessment of high-risk cutaneous stigmata on sonography. AJR Am J Roentgenol. 1998;171(6): 1687-1692.

(4.) Morris ES, Scheel MM, Lundquist KF, Raimer SS. Grouped papules on the arm of an infant: eccrine nevus. Arch Dermatol. 2000;136(4):547, 552.

(5.) Kang MJ, Yu DS, Kim JW. A case of eccrine nevus. Ann Dermatol. 2008; 20(1):29-31.

(6.) Patterson AT, Kumar MG, Bayliss SJ, Witman PM, Dehner LP, Gru AA. Eccrine angiomatous hamartoma: a clinicopathologic review of 18 cases. AJR Am J Dermatopathol. 2016;38(6):413-417.

(7.) Ost MC, Schlussel RN. A congenital scrotal mass consistent with an adnexal polyp of neonatal skin. Urology. 2002;59(4):600.

(8.) Larson KN, O'Shea P, Zedek DC, Morrell DS. Hairfollicle nevus located on the chin of an Infant: case report and review of literature. Pediatr Dermatol. 2016; 33(2):e106-e108.

(9.) Lin YT, Chen CM, Yang CH, Chuang YH. Eccrine angiomatous hamartoma: a retrospective study of 15 cases. Chang Gung Med J. 2012;35(2):167-177.

(10.) Gharpure V. Sacrococcygeal teratoma. J Neonatal Surg. 2013;2(2):28.

(11.) Oliveira NA, Alonso LG, Fanganiello RD, Passos-Bueno MR. Further evidence of association between mutations in FGFR2 and syndromic craniosynostosis with sacrococcygeal eversion. Birth Defects Res A Clin MolTeratol. 2006; 76(8):629-633.

(12.) Haydar M, Griepentrog K. Tailgut cyst: a case report and literature review. Int J Surg Case Rep. 2015;10:166-168.

(13.) Mahdavy M, Smoller BR. Eccrine nevus presenting as a perianal skin tag: a case report and review of the literature. Am J Dermatopathol. 2002;24(4):361-363.

(14.) Oh SW, Kang TW, Kim YC, Lew W. Coccygeal polypoid eccrine naevus. Br J Dermatol. 2007;157(3):614-615.

(15.) Park MY, Lee ES. Two cases of coccygeal polypoid eccrine nevi presenting as skin tags. Ann Dermatol. 2009;21(4):440-442.

(16.) Frouin E, Riviere B, Maillet O, et al. Coccygeal polypoid eccrine nevus associated with imperforate anus and unilateral multicystic kidney dysplasia. J Cutan Pathol. 2016;43(8):697-701.

Ahmad Charifa, MD; Christine J. Ko, MD

Accepted for publication April 11, 2018.

Published online December 28, 2018.

From the Department of Pathology (Dr Charifa) and the Department of Dermatology (Dr Ko), Yale School of Medicine, New Haven, Connecticut.

The authors have no relevant financial interest in the products or companies described in this article.

Corresponding author: Ahmad Charifa, MD, Department of Pathology, Yale School of Medicine, 100 York St, Apt 11P, New Haven, CT 06511 (email: ahmad.charifa@yale.edu). Caption: Figure 1. A pedunculated papule in the coccygeal region. Image courtesy of Richard J. Antaya, MD.

Caption: Figure 2. A, Polypoid fragment of skin with acanthotic epidermis and overlying hyperkeratosis. B, Within the reticular dermis, collections of well-formed eccrine ducts and glands are present (hematoxylin-eosin, original magnifications X4 [A] and X20 [B]).
Table 1. Review of Previously Reported Cases of Coccygeal Polypoid
Eccrine Nevus

Source, y             Age y/    Size, mm  Symptoms  Specific Adnexa
                      Sex
Mahdavy and Smoller,  Birth/F      5           No   Proliferation of
  (13) 2002                                         eccrine ducts and
                                                    glands
Oh et al, (14) 2007   Birth/F      3           No   Proliferation of
                                                    eccrine glands and
                                                    ducts without any
                                                    angiomatous
                                                    component
Park and Lee,         Birth/M      5           No   Proliferation of
  (15) 2009                                         eccrine glands
                                                    and ducts
Park and Lee,         Birth/F      5           No   Proliferation of
  (15) 2009                                         eccrine glands
                                                    and ducts
Frouin et al,         Birth/F      7           No   Proliferation of
  (16) 2016                                         eccrine sweat
                                                    glands surrounded
                                                    by a few healthy
                                                    adipocytes

                      Presence  Vascular  Association
                      of Other  Ectasia   With
                      Adnexa              Internal
                                          Malformation

Mahdavy and Smoller,     No       Yes          No
  (13) 2002
Oh et al, (14) 2007      No       Yes          No

Park and Lee,            No       Yes          No
  (15) 2009
Park and Lee,            No       Yes          No
  (15) 2009
Frouin et al,            No        No     Yes
  (16) 2016                               anus and
                                          unilateral
                                          multicystic
                                          kidney
                                          dysplasia)

Table 2. Differential Diagnoses of Congenital Polypoid

Eccrine Nevus

Disease              Clinical Presentation   Age Group

Sacrococcygeal       Palpable dermoid        Pediatric
teratoma
Tailgut cysts        Varied deepening on     Any age,
                     location                predominantly
                                             30-60 y
Sacrococcygeal       Prominent polypoid      Congenital,
eversion             lesion; "human tail"    neonatal
Eccrine nevi         Linear or zosteriform   Pediatric
                     papule arrangement,
                     without overlying
                     skin abnormalities
Eccrine angiomatous  Papules or nodules      Pediatric
  hamartoma          on extremities
                     accompanied by
                     hyperhidrosis and/or
                     pain
Hair follicle        Nodule on the head      Congenital
  nevus              or neck composed
                     of well-formed
                     follicles

                     Primary Anatomic
                     Location                Histopathologic
                                             Features

Sacrococcygeal       Presacral or pelvic     All 3 germ cells
teratoma                                     (ie, ectoderm,
                                             mesoderm, and
                                             endoderm)
Tailgut cysts        Presacral               Columnar,
                                             transitional, or
                                             squamous tissues
Sacrococcygeal       Lumbosacrococcygeal     Fatty tissue, nerve
eversion                                     fibers, striated
                                             muscle fibers, or
                                             cartilage
Eccrine nevi         Most commonly on the
                    for Hypertrophy or
                                             hyperplasia of
                                             eccrine glands
Eccrine angiomatous  Lower extremities       Deep dermis with
  hamartoma                                  increased eccrine
                                             units and capillary
                                             proliferation
Hair follicle        Often head or neck      Epidermal
  nevus                                      hyperplasia and
                                             many hair follicles
                                             filling the dermis
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Author:Charifa, Ahmad; Ko, Christine J.
Publication:Archives of Pathology & Laboratory Medicine
Date:Jul 1, 2019
Words:1752
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