Diagnosis and treatment of mixed salivary gland tumor previously diagnosed as cutaneous chondroid syringoma proximal to the oral commissure: A case report

Key Clinical Message

Subcutaneous tumors of the head and neck resembling cutaneous mixed tumors may be misdiagnosed pleomorphic adenomas of salivary gland origin. Physicians should consider salivary mixed tumors in the differential diagnosis for suspected cutaneous tumors.

1. INTRODUCTION

Pleomorphic adenoma, or benign mixed tumor, is the most common tumor of salivary gland origin, with ordinary sites being the palate, lip, buccal mucosa, floor of the mouth, and tongue. ¹ , ² , ³ These firm, mobile lesions comprise a majority of parotid and submandibular tumors, as well as some minor salivary gland tumors, with the posterior lateral hard and soft palate being typical locations for minor salivary gland neoplasms, followed by the upper lip and buccal mucosa. ⁴ These nodular masses have a female predilection between the ages of 30–50 and are hardly associated with pain. ⁵

Histologically, an admixture of epithelial, myoepithelial, and stromal components in various patterns and proportions is present, with the stromal element being the product of myoepithelial differentiation, taking on variable elements, that is, chondroid, myxoid, osseous, and lipomatous. Treatment for pleomorphic adenomas involves complete surgical excision to avoid multiple recurrences, as the surrounding capsule may demonstrate infiltration by tumor cells and seeding of tumor into surgical beds in the case of a more conservative resection or enucleation approach. ⁴ The prognosis is excellent, with a cure rate greater than 95% after surgical treatment, and the risk of recurrence is the lowest for neoplasms arising in the minor salivary glands. ⁴

Also typically arising in the head and neck area as a firm, slow‐growing dermal nodule, a chondroid syringoma, or mixed tumor of the skin, is a well circumscribed, multilobulated, and unencapsulated derivative of the sweat gland tumor that is morphologically identical to a pleomorphic adenoma. These benign proliferations exhibit a wide range differentiation and metaplastic changes. Specifically, apocrine mixed tumors demonstrate both follicular and sebaceous differentiation, due to their embryologic origin of the folliculosebaceous‐apocrine unit and show frequent infiltration into the surrounding tissue. ⁶ Like mixed gland tumors, mixed cutaneous tumors are comprised of epithelial, myoepithelial, and stromal elements, with the presence of heterologous differentiation of the stroma evident as osseous, adipocytic, and cartilaginous. ⁷

Clinical and morphological distinction between mixed tumors of salivary glands from those of the skin are challenging to establish. We present a case on a revised diagnosis and treatment of a benign salivary gland mixed tumor, which initially presented clinically and histopathologically as a cutaneous mixed tumor of the head and neck region.

2. METHODS

A 30‐year‐old healthy female with a past medical history of eating disorder presented with a persistent left facial mass that has been growing for the past couple of years. The patient stated she first noticed the persistent, painless “hard zit” about 7 years ago, as shown in Figure 1. A skin punch biopsy of the lesion was performed prior to the COVID‐19 pandemic and revealed a benign entity. A diagnosis of chondroid syringoma (cutaneous mixed tumor) which extended to the margins was given. However, status post biopsy of a mass continued to grow, causing discomfort on the left side of her face, difficulties with facial movements and expression, in addition to significant cosmetic concerns. The patient reported slight pain when the mass was palpated. However, there was no apparent drainage or numbness. She had consulted five other medical surgeons who had all declined to operate due to possible facial nerve damage. The case was evaluated by oral pathology, upon which the neoplasm was found to be of salivary gland origin. The diagnosis was revised to a pleomorphic adenoma. Excisional biopsy was recommended in setting of current clinical signs and symptoms.

FIGURE 1.

(A) Frontal view and (B) Lateral view of the left oral commissure show firm, diffuse, ovoid swelling, which resembles a “hard zit.”

3. RESULTS

When pressed upon intraorally, the hard, movable lump measured approximately 40 × 20 mm, as shown in Figure 2. The ovoid nodular, multilobular, firm submucosal mass laid lateral to left buccinator penetrating in the lateral, anterior, and posterior direction reaching the commissure. The mass was found to be well capsulated with no apparent facial nerve and parotid exposure and no drainage. The parotid fascia, superior mesenteric artery (SMAS), subcutaneous adipose tissue, and skin were not involved. The surgical field was defined as medial to parotid fascia and SMAS. The entire specimen was removed in one piece except a few lobules, which were detached from the main specimen and sent separately to pathology. Intraoperative pathology consult confirmed short superior long lateral markings. The specimen was sectioned and revealed cartilaginous tissue, as shown in Figure 3. There was no apparent bleeding once the specimen was removed, and the surgical site was closed in two layers with great reapproximation of wound margins, as shown in Figure 4. The two‐month postoperative examination showed unremarkable, satisfactory healing of the surgical site, as shown in Figure 5.

FIGURE 2.

Firm submucosal mass observed intraorally.

FIGURE 3.

Exposed mass after circumferential submucosal dissection.

FIGURE 4.

Surgical site closed in two layers with great reapproximation of wound margins.

FIGURE 5.

(A) Frontal view and (B) lateral view of the left side of the face 2 months after surgery.

4. DISCUSSION

To our knowledge, the present case is the first to document the misdiagnosis of a pleomorphic adenoma as a chondroid syringoma and subsequent successful management of the mixed salivary gland tumor.

H&E staining revealed a cartilaginous neoplasm comprised of uniformly dispersed inner cuboidal and outer myoepithelial cells with myxoid stroma lining branching ducts, as shown in Figure 6. The histopathological presentation of a chondroid syringoma may be identical to that of a pleomorphic adenoma, with both mixed tumors demonstrating histological diversity composed of epithelial, myoepithelial, and mesenchymal/stromal components in varied differentiation and architectural patterns. ⁵ However, the encapsulation, as shown in Figure 7, and presence of chondromyxoid stroma are more so characteristics of classic pleomorphic adenoma, as chondroid syringoma tend to generally not be encapsulated. ⁸ This feature may have proven to be difficult to capture in the initial punch biopsy, as it was not excisional and could not fully capture the presence of any capsules.

FIGURE 6.

Neoplastic myoepithelial cells in various morphological forms, including plasmacytoid, spindle cell, and epithelioid. (Hematoxylin and eosin stain, 20× original magnification).

FIGURE 7.

Lobular and encapsulated nodule showing epithelial, myoepithelial, and chondromyxoid stromal components. (Hematoxylin and eosin stain, 2× original magnification).

Other notable contrasting features between a pleomorphic adenoma and chondroid syringoma include epithelial cell differentiation towards adnexal structures, the absence of serous and mucous acinar cells, and the arrangement of epithelial cells in tubulocystic structures arranged by single or double rows in the latter. ⁹ Nevertheless, the two are histologically similar, with both demonstrating characteristic proliferation of epithelial and myoepithelial cells of the glandular ducts, accompanied by marked increases in the varied mesenchymal components of the surrounding tissue. Based on the apparent location of the tumor on the cheek close to the upper lip, which are independently the second and third most common sites for benign chondroid syringomas, and the histopathology of the lesion, the initial diagnosis of chondroid syringoma was well grounded. ⁹

Additionally, clinical features of the tumor may help redirect the diagnosis of mixed tumors. The submucosal lump measured 4 cm in diameter upon being pushed intraorally. On average, chondroid syringomas have an average diameter of ~1 cm, ranging in size from 0.5–3.0 cm. ¹⁰ Although benign chondroid syringomas greater than 3 cm in diameter have been reported, they are nevertheless an unusuality, especially when compared to the average dimensions of pleomorphic adenomas, which the majority of these neoplasms measure 2–6 cm upon excision. ¹¹ , ¹² In addition to the sheer size, the solitary, diffuse, and ovoid swelling was remarkably hard and felt most obviously from the oral cavity right under the buccal mucosa, due to the presence of densely fibrous hyaline cartilage matrix and bone formation.

Despite the slow growing nature of these neoplasms, they have the potential to grow tremendously if left untreated and undergo malignant transformation, albeit rare, resulting in carcinoma ex pleomorphic adenoma. As the malignant potential is proportional to the time the neoplasm is in situ, discovery of pleomorphic adenomas warrants prompt excision of the lesion in almost all cases. ⁴ As with most tumor resection surgeries of the head and neck, the primary concern involves preservation of the facial nerve. In the present case, the buccal branch of the facial nerve was nerve tested diligently throughout the procedure to avoid iatrogenic nerve damage. Follow‐up showed no indications of recurrence. Long‐term follow‐up for pleomorphic adenoma has been found to be unnecessary and self‐examination and patient education is considered to be sufficient, as recurrence is exceptionally rare, provided adequate excision of the tumor was achieved. ¹³

5. CONCLUSION

As pleomorphic adenomas are the most common benign salivary gland tumors and can arise from head and neck regions with salivary tissue, physicians should consider salivary mixed tumors in the differential diagnosis for suspected cutaneous tumors, even when histologically diagnosed as a chondroid syringoma. Additionally, it is imperative to perform basic intraoral examinations as part of routine head and neck examinations to aid in the clinical diagnosis of masses or refer to oral pathology for cutaneous swellings or soft tissue neoplasms that may involve the oral mucosa.

AUTHOR CONTRIBUTIONS

Haeseong Lee: Formal analysis; investigation; writing – original draft; writing – review and editing. Navid Senehi: Data curation; formal analysis; investigation; methodology; validation; visualization; writing – review and editing. Parish Sedghizadeh: Conceptualization; data curation; formal analysis; investigation; project administration; resources; supervision; validation; writing – review and editing.

CONFLICT OF INTEREST STATEMENT

No conflict of interests to disclose.

CONSENT

Written informed consent was obtained from the patient to publish this report in accordance with the journal's patient consent policy.

Lee H, Senehi N, Sedghizadeh P. Diagnosis and treatment of mixed salivary gland tumor previously diagnosed as cutaneous chondroid syringoma proximal to the oral commissure: A case report. Clin Case Rep. 2024;12:e8688. doi: 10.1002/ccr3.8688

DATA AVAILABILITY STATEMENT

Research data are not shared.