Median lingual hair heterotopia associated with pyogranulomatous glossitis in a Labrador retriever: Surgical treatment using carbon-dioxide laser

Abstract

A 9-year-old male Labrador retriever dog was presented with dysphagia and presence of hairs on the tongue. Buccal examination revealed ulcerative glossitis and lingual hairs along the midline. Ultrasound and magnetic resonance imaging of the tongue showed multiple hair shafts contained in a proliferative tissue along the midline and extending in a fistulous tract towards the right ventral aspect of the tongue at mid-length. Surgical excision was completed using a carbon-dioxide laser. Histopathological examination revealed a pyogranulomatous inflammation centered on growing hairs, confirming the diagnosis of glossitis and lingual hair heterotopia. At 10 mo after surgery, all clinical signs and glossitis had disappeared despite partial recurrence of hair on the dorsal sulcus and in the sublingual fistula.

Key clinical message:

1. Although lingual hair heterotopia usually has no clinical repercussions, associated ulcerative lesions should support imaging and biopsy.

2. Resection of the lesion using a carbon-dioxide laser resulted in a good outcome in this case, but recurrent hair growth is possible.

Congenital conditions of the tongue are uncommon in dogs; the most frequent are microglossia, macroglossia, and ankyloglossia. Acquired conditions are more common and can be neoplastic, traumatic, or inflammatory (1). Penetrating foreign bodies are among the most common cause of tongue inflammation and result in a pyogranulomatous glossitis (1).

Heterotopia, also called choristoma, is a subtype of ectopia; it refers to the ectopia of a particular tissue type that usually coexists with the original tissue. Heterotopia is not uncommon in the oral cavity in humans (2–9). For example, Fordyce syndrome, referring to the presence of heterotopic sebaceous glands in the lips or tongue, can affect up to 1 in 3 humans (10). In dogs, buccal heterotopia is uncommon, with few reports of cartilage and hairs in this location (11,12). Median lingual hair heterotopia (MLHH), or pili heterotopici mediani linguae, is a rare condition in which hair follicles and associated hair shafts are observed in the median plane of the tongue (13–15). No diagnostic protocol or preferred treatment have been proposed for this condition in dogs or humans.

This article reports a case of MLHH associated with severe pyogranulomatous glossitis in a 9-year-old Labrador retriever dog. The MLHH was not responsive to antibiotic treatment and was surgically excised using a carbon-dioxide laser.

Case description

A 9-year-old male Labrador retriever dog was presented with dysphagia, halitosis, buccal swelling, dysphagia, and ptyalism associated with ulcerative lesions and hairs on the tongue. Five months before presentation, tongue swelling and ulcerations associated with the proliferation of hairs extending along the dorsal surface of the tongue were observed by the owners, with no previous clinical signs. Before referral, the dog had been presented to 3 first-opinion practices. Each reported 2 ulcerative lesions associated with hairs: 1 lesion on the median sulcus and 1 right sublingual lesion. Before referral, the dog underwent 4 surgical removals of hairs present on the tongue and received multiple medical treatments: 1 treatment of amoxicillin/clavulanate (12.5 mg/kg, PO, q12h) and prednisolone (1 mg/kg per day, PO) for 5 d; 2 treatments of amoxicillin/clavulanic acid (12.5 mg/kg, PO, q12h) and meloxicam (0.1 mg/kg per day, PO) for 5 d; and 3 treatments of clindamycin (11 mg/kg per day, PO) and meloxicam (0.1 mg/kg per day) for 5 to 10 d. Temporary clinical improvement was observed, with recurrence of clinical signs and hair regrowth after treatment. The dog had lost 3 kg of body weight, and the owners reported the dog had a dull coat all over its body since the condition started.

The dog was referred for examination 5 mo after detection of the lesion. On admission, there were no abnormalities detected on a general physical examination. The dog was anesthetized (propofol, 4 mg/kg, IV and midazolam 0.2 mg/kg, IV, with isoflurane in oxygen) and buccal cavity examination revealed an invaginated linear ulcerative lesion on the median sulcus of the tongue with hair implantation into the lesion. All hairs had the same orientation (shafts’ apices pointing dorsally). The superficial part of the main lesion started 1 cm caudal to the lingual apex and extended caudally 8 cm along the midline (Figure 1 A). The lesion was 1 cm wide, and invagination and ulceration of the median sulcus ranged from 5 to 10 mm deep after hair removal (Figure 1 B). A similar, but focal, lesion was observed at the base of the lingual frenulum on the right side (Figure 1 C). Submandibular soft tissue swelling was attributed to tongue swelling and mandibular lymphadenomegaly.

Figure 1.

Macroscopic appearance of canine lingual median lingual hair heterotopia. A — Dorsal aspect of the tongue before surgery. Presence of hairs on the median sulcus of the tongue is evident (black arrows). B — Dorsal aspect of the tongue before surgery. Note the focal glossitis at the point of contact of the hairs (white arrowheads). C — Right sublingual aspect of the tongue before surgery. A fistula containing hairs and inflammatory exudate is present (black arrowhead).

Ultrasonographic examination of the tongue (Aplio a-series; Canon Medical Systems, Tochigi, Japan) was completed under anesthesia using a 12 to 18 MHz broadband linear transducer. Thin hyperechoic linear elements continuous with the hairs protruding on the external surface of the tongue were contained in a 15-millimeter wide and 22-millimeter deep groove of hypoechoic soft tissues extending along the tongue’s midline from 1 cm caudal to the apex to the base of the tongue. The right sublingual lesion had a similar ultrasonographic aspect and extended caudodorsally toward the main lesion (Figure 2).

Figure 2.

Ultrasound image of the tongue in cross section, showing on midline the groove of hypoechoic soft tissues (arrowheads) containing central hyperechoic linear discrete elements (arrows).

Morphine was administered and 4 punch biopsies ranging from 3 × 2 × 5 mm³ to 3 × 4 × 10 mm³ were obtained. Histopathological examination revealed a pyogranulomatous glossitis developing mainly around the hair shafts and hair bulbs, and more rarely around small, vegetal foreign bodies. All hair shafts and bulbs had a normal appearance with no suggestion of neoplastic proliferation. An antibiogram was not conducted on the lingual biopsy due to the presence of commensal oral bacteria posing a risk of contamination and misinterpretation. A combination of spiramycin (75 000 IU/kg per day, PO) and metronidazole (12.5 mg/kg per day, PO) was prescribed for 15 d to attempt to alleviate bacterial contamination. An Elizabethan collar was recommended to ensure the hairs were not originating from self-licking with a wounded tongue. After 15 d of treatment, surgery was delayed 6 wk for owner-related reasons, and antibiotic treatment continued during this period.

After 8 wk, halitosis and dysphagia had disappeared and the dog had gained 4 kg. Visual inspection of the tongue revealed persistent lingual ulcers and a slightly reduced presence of hairs compared to 2 mo earlier. On ultrasound, the lesions were similar to those previously noted. Magnetic resonance imaging (MRI) of the tongue was obtained for surgical planning purposes, using a 0.2 T low-field machine (Vet-MRgrande; Esaote, Genova, Italy). Transverse T2-weighted (T2W) and T1-weighted (T1W) pre- and post-contrast sequences were acquired (thickness: 0.5 mm; T2W: TE 100 ms, TR 5540 ms; T1W: 26 ms, 660 ms), along with a 3D T1W post-contrast sequence (thickness: 0.08 mm, TE 16 ms, TR 38 ms) to allow multiplanar reconstruction. On MRI images, the lesion appeared as a markedly T2W-hyperintense, mildly T1W-hyperintense and intensely enhancing tract, consistent with the inflammatory tissue previously identified histologically, and contained central T2W- and T1W-hypointense elements consistent with the hairs (Figure 3). The MRI allowed good visualization of the communication of the right ventral fistulous tract at the base of the tongue with the midline lesion, as well as determination of the precise extension of the lesion at the base of the tongue and anatomical localization of the lesion relative to lingual arteries and veins.

Figure 3.

Magnetic resonance images showing the midline tongue lesion in transverse section. A — T2-weighted image. B — T1-weighted image. C — T1-weighted image after intravenous injection of contrast medium (gadolinium). The midline groove is lined by T2W- and T1W-hyperintense tissues that display intense enhancement (arrowheads), and contains central T1W- and T2W-hypointense discrete elements (arrows).

Despite clinical improvement with antibiotic treatment, surgical excision of the lesion was recommended due to the high risk of recurrence after antibiotic discontinuation and the benefits of performing the surgery on healthier tissue. Resection of the lesion and associated hair shafts was done from rostral to caudal into lingual mucosa and musculosa using a 6- to 12-W noncontact super-pulsed, scanned-mode small-size carbondioxide laser (Space Vet; Deka, Manchester, New Hampshire, USA) with 2 to 5-millimeter lateral and 2 to 5-millimeter-deep margins using the MRI landmark and preserving the lingual arteries and hypoglossal nerves (Figure 4 A, B; see Video 1, available online from: www.canadianveterinarians.net). The fistula was also debrided along its fistulized tract, all the way to its junction with the median lesion. Abundant saline lavages were performed. The final incision was closed in 3 continuous layers using resorbable poliglecaprone 25 sutures (Advantime; Peters Surgical, Boulogne-Billancourt, France): 2-0 USP for the deep part of the musculosa, 3-0 USP for the superficial part of the musculosa, and 4-0 USP for the mucosa (Figure 4 C, D). An esophagostomy tube (Nutrifit, 14 Fr, 125 cm; Vygon, Ecouen, France) was placed. Mild sublingual edema occurred on the day after surgery but did not require treatment. There were no other complications and the dog was discharged from the hospital 48 h after surgery.

Figure 4.

Illustration of the surgical technique. A — Beginning the excision of the heterotopic lesion at the rostral part of the tongue. The tongue is manually stretched bilaterally to improve laser section using 3- to 5-millimeter margins. B — The excision is extended caudally. The tongue is maintained in a stretched position and excised tissue is clamped with an Allis forceps. C — Dorsal aspect of the tongue after complete removal of macroscopically visible lesion. The deep muscular part of the tongue is sutured with poliglecaprone 2-0 USP. D — Final aspect of the dorsal aspect of the tongue after surgery. Muscular and mucosal layers have been closed. No hairs or inflammatory lesions are visible macroscopically and the tongue has a normal shape.

Postoperative recommendations were as follows: feed the dog only via the tube for 15 d, limit activity for 2 wk, avoid hard objects in the mouth for 3 wk, and have the dog wear an Elizabethan collar for 3 wk. The dog was allowed to drink water. Postoperative treatment consisted of cefalexin, 15 mg/kg, PO, q12h for 5 d; prednisolone, 0.5 mg/kg, q12h for 7 d; and tramadol, 2 mg/kg, q8h for 3 d.

Histopathological evaluation of the excised tissue revealed a multifocal-to-coalescent pyogranulomatous and ulcerative glossitis centered on multiple hair shafts and, more rarely, on vegetal foreign bodies (Figure 5 A, B).

Figure 5.

Histopathologic images of the excised lingual tissue, revealing canine lingual median lingual hair heterotopia. Hematoxylin, eosin, and saffron staining; scale bars: 500 μm (A), 100 μm (B). A — Gross aspect. Hair bulbs and their associated hair shafts are observed (black arrows) with ulceration of the lingual mucosa (blue arrows). B — High-power view. Hair bulbs and their associated hair shafts are observed (arrows). Diffuse inflammatory infiltrate and neovascularization can be observed around the hair bulbs (arrowheads).

At follow-up 21 d after surgery, the owners reported the dog had no complications, a good appetite, and a less dull coat. Visually, the tongue exhibited complete healing and an absence of hair shafts. At 5 mo after surgery, there were no recurrent clinical signs and no discomfort reported when the dog was chewing or swallowing. Antibiotic treatment had not been given. Examination of the tongue was completed under sedation and revealed a small number of hairs on the dorsal sulcus and in the sublingual fistula, without associated ulceration (Figure 6). At 10 mo after surgery, no clinical signs were reported, and owner satisfaction was excellent.

Figure 6.

Dorsal aspect of the tongue 5 mo after surgery. Partial recurrence of hair is visible, but without invagination and not along the entire median sulcus (arrow).

Discussion

This is apparently the first case report of MLHH associated with a pyogranulomatous glossitis with clinical repercussions. Antibiotic treatment resulted in temporary improvement of the clinical signs and lingual lesions. However, due to a lack of complete healing and recurrence of clinical signs after discontinuation of antibiotic treatment, surgery was performed. The lesion was excised, resulting in complete resolution of clinical signs despite partial recurrence of heterotopic hairs after surgery.

In humans, hair heterotopia has been reported to occur in various locations, including the conjunctiva, buccal cavity, and bone (2,4–6,16,17). In dogs, hair heterotopia is an uncommon condition reported in the uterus and buccal cavity (13,14,18). Living follicular tissue experimentally implanted into the peritoneal cavity in dogs resulted in liver and bone marrow proliferation of hairs (19). Similarly, transplantation of isolated whisker follicles in an injured spinal cord resulted in heterotopic pigmented hair shafts in the spinal cord 90 d after implantation (20), indicating that hair follicles can develop in heterotopic locations. Lingual hair heterotopia is reported in both humans and dogs (3,8,12–15,21). In some cases, this condition is congenital, probably after abnormal embryonic development (13). However, acquired cases are sometimes associated with concomitant diseases such as dermoid cyst, teratoma, anterior trauma, or dysendocrinia (hirsutism) (3,15,21). In a case report, heterotopic hairs were observed in the tongue of a dog after suture of a lingual wound (15). In another case, no circumstantial event was reported (8). In the current case, the dog was 9 y old and the owners had not noticed the presence of hairs before manifestation of clinical signs. Although differential diagnoses for such lesions include congenital conditions such as dermoid cyst or teratoma, these were unlikely in a dog of this age and in the absence of a preexisting condition, evocative clinical signs, or histopathological findings. An acquired process was therefore expected, and despite no history of trauma, a traumatic etiology cannot be excluded as an inciting cause.

Imaging the canine tongue is challenging due to the paucity of literature for this organ. Magnetic resonance imaging is used in both humans and dogs (22–24). Despite excellent sensitivity to detect soft tissue changes, it has low specificity for discriminating between neoplastic and inflammatory processes (24). Although both MRI and ultrasound can detect hair follicles and foreign bodies, ultrasound allows a better assessment and has been successfully used to identify foreign hair material in pathologic conditions (17,25–27). In this case, MRI identified the exact extension and anatomy of the lesion for surgical planning, but hair detection was better with ultrasound than with low-field MRI. Regardless, the accuracy of ultrasound versus high-field MRI remains to be determined.

In dogs, most instances of pyogranulomatous glossitis are caused by penetrating foreign bodies (1). It is well-known that keratin outside the hair tract can act as a foreign body and provoke an intense sterile inflammatory reaction (27,28). Pyogranulomatous inflammation has been reported around hairs of MLHH, similar to that produced by foreign bodies (14). In this case, most of the pyogranulomatous reaction was centered on hair shafts, with only a small proportion centered on scarce vegetal foreign bodies. In this case, a penetrating vegetal foreign body may have initiated an inflammatory process that was subsequently enhanced by a keratin inflammatory reaction on heterotopic hair shafts.

In this dog, several antibiotic treatments failed due to the persistence of foreign bodies (hairs) into the tongue. Preoperative antibiotic treatment was prescribed to ensure a cleaner surgical site. No antibiogram was obtained due to potential commensal bacterial contamination, with antibiotics chosen based on pharmacokinetics and antimicrobial activity. Spiramycin and metronidazole were selected for their excellent buccal diffusion and aerobic and anaerobic activity (29). Although the lesion improved with this treatment, the hairs had to be surgically removed, along with their bulbs, to prevent recurrence.

A carbon-dioxide laser was chosen over electrocautery for excision of the lingual lesion due to its superiority with respect to hemostasis, operating time, and outcomes in various oral surgeries (30,31). The precise section given by the laser was helpful in not extending the section too far laterally, enabling preservation of the lingual arteries and hypoglossal nerves. The tongue was sutured in 3 layers using poliglecaprone 25 due to its rapid absorption that promoted fast healing of lingual tissue and avoided the presence of a persistent foreign body suture that could support bacteria (32). Corticosteroids were selected over NSAIDs with the aim of a greater reduction in postoperative inflammation.

Although all macroscopically visible hairs were removed during surgery, there was partial hair regrowth several months after surgery, suggesting that a portion of the active hair follicles were not surgically removed. A more aggressive approach could have created a full median section of the tongue, but this approach was not chosen because it would have been associated with more complications and a reduction in tongue width. Moreover, marginal resection of the lesion led to the complete disappearance of clinical signs with no additional antibiotic treatment and excellent owner satisfaction at 10 mo after surgery.

The authors have observed in their clinical practice several incidental cases of MLHH without inflammation or clinical consequences. For most dogs, lingual hair heterotopia is asymptomatic and surgery is generally unnecessary. However, in rare instances, glossitis, bacterial superinfection, or lingual ulcers can occur, causing clinical signs (e.g., halitosis, pain, dysphagia, dysorexia, and weight loss). Antibiotic treatment may be initially attempted to control bacterial superinfection, but some cases may require surgical excision of heterotopic and inflamed lingual tissue. Owners should be informed of the potential for relapse of the heterotopic tissue after surgery, which may require additional surgical intervention if clinical signs recur.

This is apparently the first reported case of pyogranulomatous glossitis caused by heterotopic hairs. Surgical excision completed with a carbon-dioxide laser resulted in total resolution of clinical signs.

Funding Statement

This study was funded by the IVC Evidensia Publication support grant.

The authors acknowledge IVC Evidensia for financial support.