Reconstruction of metachronous cylindroma and trichoblastic carcinoma with forehead flap

INTRODUCTION

Trichoblastic carcinoma (TC) is an extremely rare skin tumor originating from the germinative cells of the hair follicle, one of the skin adnexal structures. Due to its uncommon nature, there is no consensus regarding the general approach and treatment in the literature. Only 93 TC cases were reported in the literature between 2000 and 2020.¹ Similarly, the transformation of cylindroma, a benign skin appendage tumor, into a malignant form is also an exceptional situation.²

This study presents a case of nasal reconstruction with forehead flap of a TC manifesting a decade after the excision of a cylindroma at the identical site.

CASE REPORT

A 64-year-old male patient presented with a multinodular mass, with the largest nodule measuring 2 × 2 cm, which had been present in the right nasal wing for the last 5 years and had increased in size over the past 3 months. The patient had no systemic diseases. A lesion had been excised from the same area 10 years ago, reported as a cylindroma.

The multinodular mass was treated as a benign lesion recurrence, excised with a 1 mm surgical margin, and repaired with a full-thickness skin graft [Figure 1].

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Figure 1:

(a) Primary lesion with excision borders marked. (b) Defect after excision.

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The pathological examination of the excised lesion revealed irregular lobules, nests, and cribriform of basaloid epithelial cells, which were not invading the epidermis. These cells exhibited palisaded formation in places, increased mitosis, and contained apoptotic bodies. In addition, keratin cysts, fibrous stroma, increased fibroblast activity, papillary mesenchymal body-like formations, and calcifications were observed. Based on the immunohistochemical (IHC) positivity of CK14, CK7, Ber-P4, SMA, P53, p40, a diagnosis of TC was reported [Figure 2].

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Figure 2:

(a) Scattered palisading basaloid epithelial cells (Indicated by arrows). (b) Mitosis and apoptotic bodies (Indicated by arrows). (c) Increased fibroblastic activities and fibrotic stroma (Indicated by arrows). (d) Papillary mesenchymal body-like formations and calcifications (Indicated by arrows). (e) Positive staining with BERP4. (f) Positive staining of malignant cells with P53.

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Positron emission tomography (PET)-computed tomography (CT) imaging was performed to detect any possible distant metastases. The results detected a hypermetabolic lymph node in the right parotid gland. A fine-needle aspiration biopsy from the right parotid did not show any findings suggestive of an epithelial tumor, and the lymph node was not evaluated as malignant.

A wide local re-excision with a 7 mm surgical margin was decided by reviewing the current literature. Considering the patient’s age and general medical condition, a paramedian forehead flap was considered appropriate [Figure 3].

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Figure 3:

(a) Wide re-excision borders and flap design. (b) Defect after re-excision and flap elevation. (c) Flap inset and donor area closed primarily and partially with a full-thickness graft.

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The donor area was closed primarily, and a full-thickness skin graft was placed in the defect at the cephalic end. The flap was separated 3 weeks later, and no residual tumor was observed both clinically and pathologically. Recovery was uneventful, and all tissues healed completely.

The inferior surgical margin was reported as 0.3 cm in the re-excision pathology report, and the patient was consulted with radiation oncology. Since the surgical margin was close and the lesion developed after a mass that was previously reported as benign, it was decided that the patient would receive radiotherapy (RT) along with radiation oncology. External RT was applied to the patient’s nasal skin with a linear accelerator (6 MeV, 25 × 200 cGy). After 1 month of RT treatment, recovery was uneventful [Figure 4].

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Figure 4:

(a) Patent at post-operative 1^st month. (b) Patient at an early period after radiotherapy.

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DISCUSSION

Trichogenic adnexal tumors are a very rare group of skin tumors that mostly consist of benign neoplasms. Although Ackerman et al. attempted to categorize them based on their epithelial and mesenchymal components, this classification was not widely utilized.^3,4 Today, neoplasms originating from hair root follicles and showing follicular germinal differentiation are named as TC.³

While the etiology of TC has not been fully elucidated, a meta-analysis study by Boettler et al. reported that 87.1% of cases occur de novo.¹ Furthermore, there are cases in the literature where long-existing trichoblastoma transformed into TC.^4,5

The transformation of cylindromas into a malignant form is quite rare, but has been observed in the literature. Cylindromas have been shown to display malignant characteristics such as rapid growth, ulceration, change in color, local invasion, and lymphatic metastases.² However, asynchronous development of TC and cylindroma, as in this case, has not been described before. Although it is not certain whether TC evolved from the possible remnants of the primary cylindroma, the patient’s history, the long time frame for the transformation to occur, and identical location are suggestive of a malign transformation and would make this case a first presentation in literature. Furthermore, the rarity of both diagnoses sparks interest in further evaluation.

TC is generally seen in middle-aged patients and is observed two times more frequently in men. While it was previously thought to be more frequent on the scalp in the 2000s, today majority of the cases are reported in the head-and-neck region.¹

Since TC often shares similar physical features with other adnexal tumors, it lacks macroscopic characteristics. Clinicians mostly encounter TC as asymmetrical, irregularly circumscribed, nodular, and non-pigmented masses.⁶

The markers used in IHC studies were chosen to determine if the tumor exhibited differentiation toward the hair follicle and was of epithelial origin. The markers P53 and Ki-67 further validated findings of malignancy.

Although TC predominantly grows into the dermal and subcutaneous adipose tissue, aggressive cases with lymph node metastasis and hematogenous spread have also been reported in the literature.⁷ The rarity of such tumors, as well as the infrequent occurrence of distant metastasis and lymph node involvement, renders the establishment of a standard approach for detecting a metastasis difficult. In the literature, CT, PET-CT, dynamic contrast ultrasound, magnetic resonance imaging, and bone scintigraphy have been used to scan for metastasis, but none of them is shown to be superior.

The main approach in most current cases is excision with wide surgical margins. There are cases in the literature with surgical excision margins ranging from 0.5 to 3 cm. In majority of these cases, the lesions were excised with a 1 cm surgical margin. Recurrence was observed in only 10% of the 84 reported cases that underwent wide surgical excision.¹

Some case reports argue that Mohs micrographic surgery may yield better results than wide surgical excision, but this is not feasible in every clinic.⁶

CONCLUSION

TC is a rare adnexal skin tumor, and the number of case reports and case series available in the literature is limited. The small number of cases and the lack of scientific consensus make it difficult to formulate a treatment plan. Increasing the awareness and accumulating collective scientific experience will make it possible to construct a treatment algorithm for such a challenging malignancy.