Sir,

The proliferative trichilemmal cyst is a rare adnexal tumor that develops from the isthmic portion of the hair follicle characterized by a benign evolution in the majority of cases, yet there is a risk of malignant transformation [1]. It affects, with predilection, elderly females with preferential localization on the scalp. Malignant forms are rare [2].

The diagnosis is clinically evoked in front of an isolated nodule on the scalp with chronic evolution and recent modifications: a rapid increase in size, a painful character, and the appearance of an ulceration. The diagnosis of certainty is histological [2].

The reference treatment is based on wide surgical removal with safety margins of at least 1 cm in healthy skin. The risk of recurrence is high, requiring surveillance for fifteen months on average. Radiotherapy may be employed to limit the rate of local recurrence. Chemotherapy is necessary in metastatic forms [3].

Herein, we report the case of a 55-year-old female patient, asthmatic under treatment, who consulted for a scalp nodule evolving for the last ten years and progressively increasing in size. A clinical examination revealed an erythematous tumor, roughly rounded, well-limited, firm, and adherent to the deep plane, with hemorrhagic crusts measuring 8 cm in length in the right temporal region (Fig. 1). The examination of the lymph nodes revealed right jugulocarotid nodes.

Figure 1: (a-b) Proliferative trichilemmal cyst on the 55-year-old female patient.

A skin biopsy revealed a proliferating trichilemmal cyst without signs of invasion. An extension workup consisting of the ultrasound of the lymph nodes and a brain scan was normal. The patient underwent a large surgical resection with histologically healthy margins.

The rarity of proliferating trichilemmal cysts, their aggressiveness in malignant forms, and their accessibility to prevention, encourage the detection, screening, and diagnosis of these lesions at an early stage in order to improve the prognosis and limit aggressiveness [2].