False-Negative Tumor-Free Margins Following Mohs Surgery for Aggressive Trichoblastoma

Trichoblastomas Mimicking Basal Cell Carcinoma: The Importance of Identification and Differentiation

Trichoblastoma is a rare, slow-growing, benign cutaneous tumor derived from follicular germinative cells. Trichoblastoma commonly appears as an asymptomatic, symmetrical, well-circumscribed, skin-colored to brown or blue-black papule or nodule. It may appear clinically and histologically similar to basal cell carcinoma, making its diagnosis challenging. Even on dermoscopy, it is challenging to differentiate trichoblastoma from basal cell carcinoma. In practice, it is important to differentiate the two, because the choice of treatment and resulting prognosis differ between the lesions. Surgical biopsy to analyze histopathological and immunohistochemical differences is the gold standard for diagnosing and differentiating trichoblastoma from basal cell carcinoma. Trichoblastoma typically has a favorable prognosis, with a low incidence of recurrence, progression or association with malignancy. This paper provides a review of the epidemiology, clinical presentation, dermoscopy, histology, immunochemistry, treatment, and prognosis of trichoblastoma.

Vulvar trichoblastoma: case report and literature review

OBJECTIVE

Trichoblastomas are rare and benign tumors that arise from rudimentary hair follicles. Presentation varies from superficial plaques to papular or nodular lesions. Trichoblastomas usually arise on the head or neck. A few cases of other vulvar trichoblastic tumors such as trichofibromas and trichoepitheliomas have been reported to this day, but no such report of vulvar trichoblastoma exists.

MATERIALS AND METHODS

We report the case of a 61-year-old woman who presented with a vulvar trichoblastoma. The woman presented with a lump of the labium majus. She was managed surgically, first by wide excision of the mass followed by a second surgery consisting of a partial vulvectomy. Because surgical margins were positive and there is a potential for malignant transformation, a third surgery was performed. The margins came back negative. A literature review on trichoblastomas was performed, including its potential for malignant transformation, management, and immunohistochemistry to differentiate it from basal cell carcinoma.

RESULTS

Trichoblastomas are benign tumors that have a potential for malignant transformation. These tumors can present aggressive characteristics. Differential diagnosis from basal cell carcinoma can be difficult but is facilitated using immunohistochemistry.

CONCLUSIONS

This is the first case of vulvar trichoblastoma reported in the literature. Although it is a benign tumor, excision with negative margins is recommended because it can be difficult to distinguish from basal cell carcinoma and it has a potential for malignant transformation.

Multiple trichoblastomas in a dog

BACKGROUND

Hair follicle tumours generally present as benign, solitary masses and have a good prognosis following surgical resection.

HYPOTHESIS/OBJECTIVES

This report describes a case of multiple trichoblastomas in a dog.

ANIMAL

A 2-year-old crossbred dog presented with multiple soft cutaneous periocular, perilabial, submandibular and nasal nodules, between 2 and 9 cm in diameter, located on the right side of the face. New nodules were observed on the same side of the face at a second consultation 3 weeks later.

METHODS

Surgical resection of all nodules was performed in two procedures. Three nodules were initially resected and submitted for histolopathology and immunohistochemistry. The diagnosis was trichoblastoma for all three. At the time of the second consultation, new and remaining nodules were biopsied and the diagnosis of trichoblastoma confirmed. The dog was treated with doxorubicin and piroxicam for 30 days prior to the second surgical procedure in an attempt to reduce new tumour growth and the size of present tumours. All nodules were resected and the defects closed using rotation flaps.

RESULTS

No recurrence of the neoplasm was noted within 10 months after surgery.

CONCLUSIONS AND CLINICAL IMPORTANCE

Trichoblastomas are generally benign but can present as multiple neoplasms that may require surgical resection and may respond to chemotherapy. To the authors' knowledge, this is the first report of multiple trichoblastomas in a dog.