Proliferating trichilemmal cyst: A simulant of squamous cell carcinoma

Abstract

Comparison of 50 proliferating trichilemmal cysts with 50 "ordinary" trichilemmal cysts indicated that both types almost invariably occurred on the scalps of women, were diagnosed clinically as cysts, followed a benign course, and featured trichilemmal keratinization. A spectrum was observed from trichilemmal cyst with minimal hyperplasia, to full-blown proliferating trichilemmal cyst. Occasionally, patients had ordinary trichilemmal cysts on their scalps associated with a proliferating trichilemmal cyst. In addition to trichilemmal keratini-zation, which is characteristic of the follicular isthmus, proliferating trichilemmal cysts showed a wider range of differentiation, including features of the follicular infundibulum, the lower nonkeratinizing portion of the follicular outer root sheath, and sebaceous cells. Intense inflammatory infiltrate and cellular atypia, sometimes of significant proportions, were also seen in proliferating trichilemmal cysts. It is concluded that trauma and inflammation may induce a trichilemmal cyst to proliferate and show a broader spectrum of pilosebaceous differentiation and cellular atypia of pseudocarcinomatous proportions, while maintaining its benign biologic behavior. Cancer 481207-1214,1981. HERE IS A PECULIAR benign cutaneous growth that T usually resembles a cyst clinically, but is often histologically misinterpreted as squamous cell carcino-ma. Our purpose here is to analyze the clinical and his-tologic features of a large series of proliferating trichilemmal cysts. Evidence is presented on the pathogenetic relationship between proliferating and ordinary trichilemmal cysts. Emphasis is placed on the wide range of pilosebaceous differentiation and striking cellular dysplasia encountered in proliferating cysts, compared with the restricted pattern of ordinary trichilemmal cysts. Material and Methods Fifty proliferating trichilemmal cysts were collected during the past nine years. Minimal clinical data required for inclusion in this study were the sex and age of the patient and the anatomic site of the growth. Histologic sections were reviewed in all cases. For comparative purposes, 50 uncomplicated trichilemmal cysts were studied. Clinical Features Among the 50 patients with trichilemmal cysts, 84% were women; 90% of the lesions were on the scalp (Fig. l), two were on the back, and one each on the forehead (Fig. 2), wrist, and chest (Fig. 3). The age range was 27-83 (median 59) years. One patient was in the third, 2 in the fourth, 9 in the fifth, 14 in the sixth, 14 in the seventh, 6 in the eighth, and 4 in the ninth decade. The duration ranged from one-half to over 20 (median 2) years. Sometimes, a cystic lesion had been present for years, then slowly enlarged. In 94%, the clinical diagnosis was "sebaceous," pilar, trichilem-mal, or epidermoid cyst; in two patients it was squam-ous cell carcinoma and in one, dermatofibroma. For about 50% of the patients, there was intermittent discharge or inflammation; several growths were eroded or ulcerated. Occasionally there was' bleed...

Peri-Genital Proliferating Trichilemmal Cyst: A Clue to Underlying Malignancy

“…[4] Approximately 90% of patients with TCs present with scalp lesions which presents as a single lesion 1 to 10 cm in size, elastic firm to soft in consistency, over the scalp, although lesions up to 25 cm have been reported. [3] About 84% of the patients are greater than 50 years of age with predominance of females. PTC's tend to occur after the age of 60years [5] but they have been reported in individuals as young as 18 years.…”

“…[2] a b PTC is thought to originate from the trichilemmal cyst (TC) following some trauma and inflammation. [1,3] PTC's can occur de novo. Although PTC is considered biologically benign, they may be locally aggressive with potential of recurrences and malignant transformation with metastasis to lymph nodes and internal organs.…”

“…It is thought to arise from trichilemmal cyst with histological hallmark of trichilemmal keratinisation. [2] Histologically this tumour have a capacity to imitate squamous cell carcinoma [3] and clinically PTC has the potential for malignant transformation as well as recurrences after surgical confiscation. [2] Scalp is frequently involved (>90% cases) site in individuals of more than 60 years of age, especially elderly females.…”

“…[2] Scalp is frequently involved (>90% cases) site in individuals of more than 60 years of age, especially elderly females. [3] PTC has various synonyms like pilar tumor of the scalp, giant hair matrix tumor, hydatidiform keratinous cyst, trichochlamydocarcinoma, and invasive hair matrix tumor. [2] We present a case of 70 year old elderly female who had a PTC at uncommon site in the perigenital area which later progressed to cutaneous squamous cell carcinoma of that region with metastasis to regional lymph nodes.…”

Low Grade Malignant Proliferating Pilar Tumor Arising from Breast Skin Simulating Squamous Cell Carcinoma, a Case Report

“…These tumors are classified into three groups: benign, locally aggressive, and malignant [3]. Like pilar cysts, PTTs also generally present on the Scalp [4]. Other locations, although much less common, have been reported in the literature: these include the neck, trunk, groin, mons pubis, vulva, and gluteal region; the upper and lower extremities, including the elbow, the dorsum of the hand, and the index finger; the face, including the forehead, nose, eyelid, lip, and intraorally [4][5][6][7][8][9][10][11].…”