j . Comp. Path. 1997 Vol. 117, 267-270

SHORT PAPER

H e t e r o t o p l c H a i r s in t h e T o n g u e o f T w o D o g s

J. P. Teifke and C. V. L6hr Institut fiir Veterini~r-Pathologie, Justus-Liebig-Universitiit, Frankfurter Str. 96,

D-35392 Giessen, Germany

- j C P

S u m m a r y

The occurrence of hairs in the median sulcus of the tongue in two dogs, a 7-year-old Rottweiler and a 10-year-old Cocker spaniel, is reported as an incidental observation at necropsy. The gross pathology of both cases and the histological and scanning electron microscopical findings in one case indicated a heterotopic development of the hairs, with secondary in- flammation. The term pili heterotopici mediani linguae is suggested.

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Introduction

Congenital anomalies of the tongue are rare in domestic animals. Apart from macroglossia, lingua bifida, linguae accessorii and epitheliogenesis imperfecta, the most common developmental malformation in dogs is the so-called "bird tongue", a recessive autosomal defect characterized by a narrow tongue, leaving the puppies unable to swallow (Zakrzewski, 1970; Jones and Hunt, 1983; Barker et al., 1993). In man, heterotopias in the oral cavity are not uncommon. The Fordyce-syndrome, with heterotopic sebaceous glands in lips, gums or tongue, occurs in one in four of all women and one in three of all men (Seifert, 1966). Well known also are dermoid cysts, which are generally found in the median of the tongue, most often sublingually; to a lesser extent, similar cysts are found intramuscularly. They develop from remaining middle parts of the branchial furrow or neck cove. As inclusions of the ectoderm into the parotid region or tongue, they are composed of stratified squamous epithelium sur- rounded by thick layers of connective tissue, mostly containing sebaceous material and hairs. Some of these branchial cysts, covered by a mucous membrane and filled with a "muddy" secretion, are called mucous cysts (Seifert, 1966; Barker et al., 1993). The main causes of deep glossitis in the dog are penetrating plant fibres, burrs or quills that induce exuberant granulomas (Barker et al., 1993). During the past 6 years we have observed two cases of hairs growing in the tongue of dogs. The first dog (no. 1) was a 10-year-old female Cocker spaniel, which was paralysed as the result of a prolapsed intervertebral disk, with extrusion of disk material into the vertebral canal between the 12th and 13th thoracic vertebrae. The animal was humanely destroyed and the tongue was examined macroscopically. The second case

0021-9975/97/070267 + 04 $12.00/0 �9 1997 W.B. Saunders Company Limited

268 J.P. Tei fke a n d C. V. Ltihr

Fig. 1. Tufts of hairs in the median sulcus of the tongue of dog no. 1. Bar, 0'7 cm.

Fig, 2. Tufts of hairs in the median sulcus of the tonguc of dog no. 2. Bar, 0"5 cm.

H e t e r o t o p i c H a i r s i n t h e T o n g u e o f T w o D o g s 269

Fig. 3.

Fig. 4.

Fig. 5.

[tistological section of pill hetemtopici mediani linguae in dog no. 2. Cross-sections of hairs of difli:rcnt diameter are grouped together resembling hair beds wilhin the nmscular body of the tongue, with peritrichal pyogranulomatous inIlammalicm. Haematoxylin and eosin (HE). Bar, 9(I gin. ( x 80). Histological section ofpili heterotopici mediani linguae in dog no. 2. A thick layer of cuboidal ceils surrounds the hair, resembling the outer root sheath. Cells of the outer root sheath are undergoing trichilemmal keratinization without forming keratohyalin granules. HE. Bar, 65 gm. (x 125). Scanning electron micrograph ofpili heterotopici mediani linguae in dog no. 2. The cuticular cells are overlapping each other. The orientation is the same as is found in the skin. Bar, 25 gm. ( x 240).

(no. 2), a 7-year-old female Rottweiler, was examined macroscopically, histo- logically and by scanning electron microscopy. This dog was admitted to the Faculty of Veterinary Medicine, Justus-Liebig-Universit~t Giessen, with a history of chronic progressive lameness of the left foreleg. An osteolytic tumour of the left humerus was diagnosed radiographically, and because of a poor prognosis the animal was destroyed. At necropsy, a tumour, 9 cm in diameter, was found in the proximal part of the left humerus and diagnosed histo- pathologically as an osteosarcoma.

Tufts of brown-black hairs up to 1 cm long were observed over a distance of 10 cm in dog no. 1 (Fig. 1) and 2"5 cm in dog no. 2 (Fig. 21, in the middle part of the median sulcus of the tongue. In dog no. 2, transverse histological sections revealed variable numbers of hairs deep within the muscular body of the tongue. Hairs of different diameter were found in clusters, resembling hair beds (Banks, 1986) composed of main and secondary hair-shafts, with only the thicker hair shafts containing a honeycomb-like medulla (Figs 3, 4). In the deeper parts of the tongue, thick layers ofcuboidal cells were found surrounding the hairs and therefore resembling the outer root sheath. These layers showed

270 J.P. Teifke and C. V. L6hr

trichilemmal keratinization without the formation of keratohyalin granules (Fig. 4) as seen in the middle portion of hair follicles in the skin. In the more superficial parts of the tongue, the hairs were surrounded only by a sheath of connective tissue. No sebaceous glands or arrector pili muscles could be found. For this reason the term dermoid cyst was not applied. Occasionally, single hairs or complete hair beds were surrounded by neutrophils and macrophages (Fig. 3), due to a pyogranulomatous inflammation similar to that produced by foreign bodies.

By scanning electron microscopy, cuticular cells were shown to overlap each other, like slates on a roof (Fig. 5), as is found in hairs growing in the skin (Banks, 1986). It seems unlikely, therefore, that the hairs had been taken up accidentally by licking and penetrated the mucosa in the median sulcus. However, one such case of hair-implantation after injury to the tongue has been described (Reifinger, 1994). Histological and scanning electron microscopical examination of dog no. 2 proved for the first time in this species, that the hairs developed in situ, and confirmed the earlier observation of Swanson (1981). The surrounding pyogranulomatous inflammation was of a secondary nature, and we suggest the term pili heterotopici mediani linguae to describe the underlying abnormality.

A c k n o w l e d g m e n t s

We thank Prof. Dr. Dr. h. c. E. Weiss for useful discussion and review of the manuscript and Ute Zeller for assistance in photography.

References

Banks, J. W. (1986). Integumentary system. In: Veterinary Histology, 2nd Edit., Williams & Wilkins, Baltimore, pp. 348-379.

Barker, I. K., van Dreumel, A. A. and Palmer, N. (1993). The alimentary system. In: Pathology of Domestic Animals, K. V. F. Jubb, P. C. Kennedy and N. Palmer, Eds, 4th Edit., Academic Press, San Diego, pp. 1-4.

Jones, T, C. and Hunt, R.D. (1983). The digestive system. In: Veterinary Pathology, 5th Edit., Lea & Febiger, Philadelphia, pp. 1350-1353.

Reifinger, M. (1994). Implantation von Haareh in die Zunge von Hunden nach Schnittverletzung. Berliner und Miinchener 77erarztliche Wochenschrift, 107, 35.

Seifert, G. (1966). Mundh6hle, Mundspeicheldrase, Tonsillen und Rachen. In: Spezielle Pathologische Anatomie, W. Doerr und E. Uehlinger, Eds, Springer, Berlin, Hei- delberg, New York, pp. 23-25.

Swanson, E. A. (1981). Hair follicles in the canine tongue. Oral Surgery, Oral Medicine, Oral Pathology, 51,277-280.

Zakrzewski, A. (1970). Mund- und Rachenh/Shle mit Speicheldrase. In: Handbuch der SpezieUen Pathologischen Anatomie der Haustiere, 3rd Edit., E. Joest, Ed., Paul Parey Verlag, Berlin und Hamburg, pp. 16-19.

I Received, February 20th, 19971 Accepted, J @ 28th, 1997 j