EC Clinical and Medical Case Reports

Introduction: Trichilemmal cysts, also known as pillar cysts, are benign intradermal or subcutaneous lesions that derive from the outer root sheath of the hair follicle. They occur in 5-10% of the population, show a predominance of females, and may have an autosomal dominant inheritance pattern or occur sporadically.

They appear more frequently on the scalp in 90% of cases and the rest may appear on the face, trunk, groin and extremities less frequently. Histopathologically, trichilemmal cysts contain abrupt keratinization and broad eosinophilic cytoplasm without a granular layer.

Ultrasound is the study of choice with a sensitivity of 99% and a specificity of 100%. The treatment of choice is surgical, and complete resection of the cyst is performed, generally with a good prognosis.

Objective: Presentation of a case on the treatment used for a trichilemmal cyst at the Ticomán General Hospital of the Ministry of Health of Mexico City to the entire surgical community.

Results: A 63-year-old female patient presented to the general surgery outpatient clinic at the Ticomán General Hospital of the Ministry of Health, who presented with a progressive increase in volume of 10 years of evolution in the posterior parietal region with slight pain on palpation. On questioning he does not present any important antecedent.

Physical examination with vital signs within normal parameters, conscious, oriented, at the level of the scalp with the presence of an increase in volume in the posterior parietal region of approximately 7 cm, with well-defined borders, slightly mobile, not adhering to deep planes, without presenting changes in color, slightly painful to palpation and pressure, rest of the normal examination.

A wedge incision was made on the cyst with complete resection of the cyst of 5 x 5 cm, having exposure of the calota, leaving a defect of approximately 8 cm long with a depth of 1.5 cm, with inability for the primary closure of the defect, so it was decided to take a graft of full thickness of the inguinal region, the graft was fixed with nylon 4-0 without any complication during the procedure, The hemostasis of the tissue is verified, as well as the capillary filling of the graft, being adequate during the immediate postoperative period.

A surgical specimen was sent to pathology reporting a solid cystic mass, with well-defined borders, non-infiltrating, squamous epithelium that presented trichilemmal-type keratinization.

With follow-up and management through the outpatient clinic at 7, 14, 21 days, one month and 3 months.

Discussion: Pinkus in 1968 described the portion of the external root sheath between the pons and the opening of the sebaceous duct as the trichilemmal comparing it to the neurilemmal sheath (Schwann's sheath) that covers the nerves. The trichilemmal is keratinized without the formation of keratohyalin granules and the individual cells increase in volume and vertical diameter instead of flattening as they do in the epidermis. Cysts with a lining that is keratinized in the same way as trichilemmal are called trichilemmal cysts.

They appear most frequently on the scalp in 90% of cases, the rest may appear on the face, trunk, groin and extremities less frequently. Trichilemmoma cysts are present in both non-neoplastic and neoplastic forms, where the latter is known as proliferating trichilemmal cyst which is a rare neoplasm, occurs more frequently in older women and corresponds to 0.1 to 3% of benign skin tumors.

Both trichilemmal cysts and proliferating trichilemmal cysts have a trichilemmal type of keratinization and can occur simultaneously.

Although computed tomography and magnetic resonance imaging have been used for the study of cysts, ultrasound is the study of choice with a sensitivity close to 99% and a specificity of 100%.

The treatment of choice for CTs is usually surgical, and complete resection is performed with margins of 1 cm. Your prognosis is good when the resection is complete. Among the main complications that can occur after cyst resection is bleeding, pain, infection or recurrence of the cyst. In the case reported in this case report, one of the expected complications was graft rejection or necrosis.

Conclusion: Trichilemmal cysts are benign lesions and can rarely transform into malignancies. The head and neck are the most common sites that are affected. There are no established guidelines for the treatment of trichilemmal cysts.

 Keywords: Graft; Cyst; Scalp; Trichilemmal

1. Headington IT and French AJ. “Primary neoplasms of the hair follicle”. Archives of Dermatology 86 (1962): 430-441.
2. Pinkus H. “Static and dynamic histology and histochemistry of hair growth”. In: Biopathology of Pattern Alopecia. Proceedings of the International Symposium held in Rapallo, Italy, July 28^th (Ed. by A. Baccaredda-Boy, G. Moretti and I.R. Frey). Karger, Basel/New York: 69-81.
3. Maurer FR. “The epidermis and its descendants”. Wilhelm Engelmann, Leipzig (1895).
4. Pinkus H. “'Sebaceous cysts' are trichilemmal cysts”. Archives of Dermatology5 (1969): 544-555.
5. Chang SJ., et al. “Proliferating trichilemmal cysts of the scalp on CT”. American Journal of Neuroradiology 3 (2006): 712-714.
6. Leppard BJ., et al. “Hereditary trichilemmal cysts. Hereditary pilar cysts”. Clinical and Experimental Dermatology 1 (1977): 23-32.
7. Ramaswamy AS., et al. “Morphological spectrum of pilar cysts”. North American Journal of Medicine and Science 2 (2013): 124-128.
8. Amarillas ED and Metlich MA. “A large trichilemmal cyst of the scalp skin of the posterior region of the skull. Report of a clinical case”. Revista Mexicana de Cirugía Bucal y Maxilofacial 8 (2012): 59-63.
9. Mathis ED., et al. “Malignant proliferating trichilemmal tumor”. American Journal of Clinical Oncology 4 (2001): 351-353.
10. Requena L., et al. “Proliferating trichilemmal tumor”. In: WHO Classification of Skin Tumors 4. Lyon, France: IARC Press (2018): 196-197.
11. Balasundaram P., et al. “Evolution of epidermoid cyst into dermoid cyst: embryological explanation and radiological-pathological correlation”. Neuroradiology Journal 2 (2019): 92-97.
12. Sáez E., et al. “Proliferating trichilemmal tumor: a case report and literature review”. Rev Otorhinolaryngol Cir Head Neck 78 (2018): 305-308.
13. Kang SJ., et al. “Proliferating trichilemmal cyst of the eyelid”. American Journal of Ophthalmology 6 (2007): 1065-1067.
14. Brownstein M. “Hybrid cyst: a combined epidermoid and trichilemmal cyst”. Journal of the American Academy of Dermatology 6 (1983): 872-875.
15. Wortsman X., et al. “Guidelines for performing dermatologic ultrasound examinations by the DERMUS Group”. Journal of Ultrasound in Medicine 3 (2016): 577-580.