Morphological spectrum of pilar cysts

Pilomatrixoma and its Imitators

Introduction: Pilomatrixomas are benign neoplasms derived from hair follicle matrix cells. They are among the most common soft tissue head and neck tumors of childhood. Pilomatrixomas are typically isolated, slow-growing, firm, nontender masses that are adherent to the epidermis but mobile in the subcutaneous plane. This clinical presentation is so characteristic that many experienced surgeons will excise suspected pilomatrixomas without prior imaging. We reviewed the results of this approach to determine whether physical examination alone differentiates pilomatrixomas from other similar soft tissue lesions of the pediatric head and neck. Methods: Computerized review of all pilomatrixomas over a 20-year period in a single academic pediatric otolaryngology practice. Results: 18 patients presented to our pediatric otolaryngology practice between 2001 and 2021 with historical and physical findings consistent with pilomatrixoma. Of the 18 patients, 7 were male and 11 were female. Ages ranged from 1.5 to 14 years, with a mean of 7.5 years. Most of the lesions (12) were located in the head and face, while the rest (6) were found in the neck. All patients were treated with complete surgical excision. Pathology confirmed pilomatrixoma in 15 patients. The remaining 3 children were found to have an epidermal inclusion cyst, a ruptured trichilemmal cyst, and a giant molluscum contagiosum lesion, respectively. One additional patient presented with a small lesion of the auricular helix that was thought to be a dermoid cyst, but proved to be a pilomatrixoma on histologic examination. Discussion: As pilomatrixomas are common and have a very characteristic presentation, surgical excision without prior diagnostic imaging will lead to correct treatment in the majority of cases. High resolution ultrasonography can help to confirm the diagnosis preoperatively, but is not definitive in large case series. Most of the cystic lesions that imitate pilomatrixoma will ultimately require surgical excision.

Atypical Presentation of Pilar Cyst Over the Volar Aspect of the Thumb: A Case Report and Review of Literature

Pilar cysts are derived from the outer layer of the root sheath of hair follicles. They were conventionally thought to arise from hair-bearing skin like the scalp. However, this notion has been refuted recently. Pilar cysts of the hand are extremely rare, with only a few case reports in the literature. We report the case of a 40-year-old male patient, with no known medical co-morbidities, who presented with a swelling over his left thumb. It was occasionally painful, and caused difficulty in grasping objects. Physical examination revealed a 2.5 x 1.5 cm swelling over the volar aspect of the thumb, at the level of the proximal phalanx. MRI revealed the presence of a well-defined cystic lesion superficial to the flexor tendons. The possibility of an epidermal cyst was considered, and the patient was advised surgery in view of his symptoms and progression in the size of the swelling. He underwent excision of the lesion along with a segment of adherent skin. Histopathological examination of the lesion revealed the presence of a pilar cyst. The patient did not have recurrence of symptoms following surgery, and was found to be doing well at the three-year follow-up. This case report urges a re-thinking of the possible origins of pilar cysts from atypical locations.

Adnexal neoplasms of the eye

Adnexal neoplasms of the eyelid encompass a wide variety of benign and malignant tumors of sebaceous, follicular, and sweat gland origin. Due to the specialized structures of the eyelid, these neoplasms present differently when compared with those of other locations. Although most dermatologists and ophthalmologists are familiar with the commonly reported adnexal tumors of the eyelid, such as hidrocystoma, pilomatrixoma, and sebaceous carcinoma, many other adnexal neoplasms have been reported at this unique anatomic site. Accurate and timely identification of these neoplasms is essential, as alterations of eyelid anatomy and function can have a negative impact on eye health, vision, and quality of life. We review the clinical and histopathologic features of common and rare eyelid adnexal neoplasms and discuss proposed treatment options.

The Value of Ultrasound for Differentiating Trichilemmal Cysts From Epidermoid Cysts

OBJECTIVES

This study was aimed to evaluate the diagnostic performance of ultrasound (US) in differentiating trichilemmal cysts (TCs) from epidermoid cysts (ECs).

METHODS

Based on clinical and ultrasound features, a prediction model was established and validated. 164 cysts in the pilot cohort and another 69 in the validation cohort diagnosed with TCs or ECs histopathologically were evaluated. The same radiologist performed all ultrasound examinations.

RESULTS

For clinic features, TCs tended to occur in females compared with ECs (66.7 vs 28.5%; P < .001). In addition, TCs were prone to occur in the hairy area compared with ECs (77.8 vs 13.1%; P < .001). For ultrasound features, the internal hyperechogenicity and cystic change were more likely to appear in TCs in comparison with ECs (92.6 vs 25.5%; P < .001; 70.4 vs 23.4%; P < .001, respectively). Upon the features mentioned above, a prediction model was established with the areas under the receiver operating characteristic curves of 0.936 and 0.864 in the pilot and validation cohorts, respectively.

CONCLUSIONS

US is promising for differentiating TCs from ECs and is valuable for their clinical management.

Pilar Cyst From a Maxillofacial Surgeon's Perspective: A Case Report and Review of Literature

Pilar cysts/trichilemmal cysts are benign lesions that arise from the hair follicle epithelium. The commonest area of occurrence is the scalp but it can also occur in the head and neck region. The pilar cyst grows at a prolonged rate. They are relatively rare and occur in about 10% of the population. They appear in the region of high concentrations of hair follicles. A 75-year-old male patient came to the Department of Oral and Maxillofacial Surgery with a chief complaint of swelling on the left side of the face for the past one year. Cytological examination revealed an infected cystic lesion. Computed tomography (CT) showed a well-defined lesion in the left temporal region. After surgical excision of the lesion, it was sent for histopathological examination. Excisional biopsy revealed a pilar cyst. We report a rare case of pilar cyst in the left temporal region in a patient who was previously operated on for osteomyelitis of the left side of the mandible up to the coronoid process. These cysts may mimic temporal space infection and lead to an incorrect treatment plan.

A Detailed Review of Surgical Management of Uncommon Cutaneous Disorders

A variety of cutaneous disorders can present to the general surgeon either directly or by referral for surgical intervention. Some conditions are commonly seen and operated on by general surgeons which include lipoma, epidermoid cyst, etc. On the other hand, some are uncommon conditions like dermatofibrosarcoma protuberans and chondroid syringoma which require a high index of suspicion to diagnose. Most general surgeons are not familiar with the latest guidelines to treat such uncommon conditions. In this article, we provide a review of uncommon cutaneous disorders requiring surgical intervention that were encountered at our high-volume tertiary care center and a discussion about their etiology, presentation, diagnosis, management and follow-up with one case report of each condition. The objective of this article is to familiarize the general surgeon with these cutaneous disorders which though uncommon, will present in their practice at some point.

Giant, Bleeding, and Ulcerating Proliferating Trichilemmal Cyst, With Delayed Treatment Due to Coronavirus Outbreak: A Case Report and Review of the Literature

We report a case of a large, ulcerating proliferating trichilemmal cyst in a 76-year-old woman, with clinical, radiological, macroscopic, and microscopic correlation. The outbreak of the Coronavirus pandemic delayed her treatment. We review the literature on proliferating trichilemmal cysts, which are relatively rare tumors, which, generally, are considered benign. However, we found a high rate of malign cases, which stresses the importance of rapid surgical excision and histological diagnosis. Even though our proband had delayed treatment, the tumor did not transform into a malignant form.

Imaging findings of trichilemmal cyst and proliferating trichilemmal tumour

PURPOSE

The purpose of this study was to evaluate computed tomography and magnetic resonance imaging of benign trichilemmal cysts and proliferating trichilemmal tumours.

METHODS

Nineteen histologically confirmed cutaneous lesions with trichilemmal keratinisation (12 trichilemmal cysts and seven proliferating trichilemmal tumours) were enrolled. Among them, 10 lesions (six trichilemmal cysts and four proliferating trichilemmal tumours) were examined by computed tomography, while 13 lesions (eight trichilemmal cysts and five proliferating trichilemmal tumours) were examined by magnetic resonance imaging. Computed tomography and magnetic resonance imaging characteristics were retrospectively reviewed.

RESULTS

Sixteen lesions (84%, 10 trichilemmal cysts and six proliferating trichilemmal tumours) occurred on the scalp. Lobulated margins were observed in five lesions (26%, three trichilemmal cysts and two proliferating trichilemmal tumours). With respect to computed tomography attenuation, calcification (>200 Hounsfield units) was observed in seven lesions (70%, five trichilemmal cysts and two proliferating trichilemmal tumours), hyperdense areas (≥80 and ≤200 Hounsfield units) in six (60%, three trichilemmal cysts and three proliferating trichilemmal tumours), and soft tissue density areas (<80 Hounsfield units) in nine (90%, five trichilemmal cysts and four proliferating trichilemmal tumours). On T1-weighted images, intratumoral hyperintensity was only observed in eight trichilemmal cysts but no proliferating trichilemmal tumours (100% vs. 0%, P<0.01). On T2-weighted images, hypointense rim and intratumoral hypointensity was observed in all 13 lesions (100%, eight trichilemmal cysts and five proliferating trichilemmal tumours), and linear or reticular hypointensity was observed in 10 (77%, six trichilemmal cysts and four proliferating trichilemmal tumours).

CONCLUSION

Trichilemmal cysts and proliferating trichilemmal tumours predominantly occurred on the scalp with calcification, and usually exhibited linear or reticular T2 hypointensity. Intratumoral T1 hyperintensity may be a useful imaging feature for differentiating trichilemmal cysts from proliferating trichilemmal tumours.

Multicameral Steatocystoma Simplex of the Caruncle

A yellow cyst of the caruncle in a 68-year-old man displayed the characteristic sebaceous glands and sebocytes of steatocystoma within the cyst wall, with a unique configuration of multiple branching compartments. The cyst lining was of trichilemmal character, lacking a keratohyalin granular layer, and replicated the immunohistochemical characteristics of a previously reported caruncular steatocystoma with the exception of a positive trichilemmal marker, calretinin, in the present case. Four previous cases of caruncular steatocystoma have been described, only one of which incorporated immunohistochemical analysis. Steatocystoma develops from a sebaceous gland duct, which displayed in this case multiple chambers subdividing what is usually a single round lumen.

Dermatopathology of Cutaneous Cystic Lesions: A Practical Review With Diagnostic Clues and Pitfalls

BACKGROUND

Cystic lesions are common in the daily practice of dermatologists and dermatopathologists, and in most cases, a straightforward diagnosis can be done. Yet, some variants and situations may cause diagnostic problems or carry prognostic and/or systemic implications.

OBJECTIVE

To review the histopathological features of the most frequent cystic lesions, either true cysts or pseudocysts, and provide some clues and pitfalls to bear in mind for troublesome situations such as solid-cystic tumors; uncommon variants; incidental findings; artifactual, reactive, or infectious cavities; cysts as a warning of systemic and hereditary diseases; and malignant cystic tumors, either primary or metastatic.

METHODS

The histopathological diagnostic criteria of most cystic lesions and their potential caveats will be discussed, offering some diagnostic clues.

RESULTS

Cystic lesions of the skin can primarily be classified into true cysts and pseudocysts. The most frequent pseudocysts are sinus pilonidalis and mucin-filled cavities. True cysts can be divided according to their epithelial origin or differentiation into epidermal/pilar cysts, cysts from glandular appendages, and from embryonic remnants. Diagnostic dilemmas and possible pitfalls in cystic lesions are reviewed, offering some keys to solve them.

CONCLUSIONS

Knowledge of the histopathology of cystic lesions contributes to their correct diagnosis, improving the management of patients.

Proliferating trichilemmal cyst with clinical, radiological, macroscopic, and microscopic correlation

Proliferating trichilemmal cyst is an uncommon neoplasm arising from the follicular isthmus, whose histopathological hallmark is the presence of trichilemmal keratinization. We describe a case of proliferating trichilemmal cyst in a 57-year-old woman with a broad clinical, radiological, macroscopic and microscopic correlation.

Rare Presentation of Pilar Cyst of the Thumb

Pilar cysts are common cysts on the scalp and hair bearing area of the body. We found one such cyst on the dorsum of the thumb. There have been previous reports of them in the finger tips as a very rare occurrence. The site of this lesion supports the theory of a possible origin from the nail matrix. These lesions, even when found at unusual sites should have pilar cyst as a differential diagnosis. They must always be excised and subjected to careful histopathology to rule out proliferating trichilemmal cysts, which carry a rare risk of malignancy.

Trichilemmal Cyst: Clinical and Sonographic Features

OBJECTIVES

In this study, we retrospectively reviewed the clinical and sonographic features of patients with trichilemmal cysts.

METHODS

Sonographic findings of 54 cases of trichilemmal cysts were retrospectively analyzed from 50 patients, including 4 cases of proliferating trichilemmal cysts. Associated factors of internal calcification-positive cases were also evaluated.

RESULTS

The mean age of the 50 patients was 43.4 years (range, 15-80 years) and the female-to-male ratio was 1.3. Overall, 68% of the trichilemmal cysts in the 54 lesions were located in the scalp, and 15% were located in the extremities. All 54 lesions were preoperatively examined by sonography and showed well-defined, oval-shaped structures located in subcutaneous soft tissues close to the dermis. Of the 54 lesions, 72% were hypoechoic masses, 89% were heterogeneous, and 65% had internal calcification. Among the internal calcification-positive cases, the mean age of the patients was 43.4 years, and the female-to-male ratio was 0.6. Of these lesions, 83% were located in the scalp. We did not find any significant association between calcification, age, or sex (P = .993 and P = .99); however, lesions present in the scalp were significantly associated with internal calcification (P = .005). 81% of the 54 lesions displayed posterior enhancement. but the color Doppler sonography of all lesions revealed no vascularization.

CONCLUSIONS

Trichilemmal cysts should be considered to diagnose of well-defined, hypoechoic lesions with internal calcification and posterior sound enhancement in the subcutaneous soft tissues of the scalp or extremities upon sonography.

Laryngeal Pilar Cyst Masquerading as an Internal/External Laryngocele

Objectives:

This study aimed to document and describe a case of a laryngeal pilar cyst and to review the literature.

Methods:

We describe the case of a 65-year-old woman with a laryngeal pilar cyst presenting with occasional ear pain and positional dyspnea, with imaging studies suggesting external/internal laryngocele. We also review the existing clinical literature.

Results:

Pilar cysts are adnexal skin lesions most commonly found in the scalp of elderly women. They generally have a benign course, but in rare instances single or multiple foci of proliferating cells can lead to the neoplastic formation of proliferating trichilemmal cysts, which carry malignant potential. Depending on the location of the cyst, pilar cysts may also present functional challenges for the patient.

Conclusions:

Herein, we describe a pilar cyst in and around the larynx appearing initially as a laryngocele. Pilar cysts may present surrounding the larynx and may be mistaken for a vast array of pathologies. It is important to keep the differential broad when evaluating laryngeal masses.

Congenital Giant Keratinous Cyst Mimicking Lipoma: Case Report and Review

Epidermal cysts represent the most common cutaneous cysts. They arise following a localized inflammation of the hair follicle and occasionally after the implantation of the epithelium, following a trauma or surgery. Conventional epidermal cysts are about 5 cm in diameter; however, rare reports of cysts more than 5 cm are reported in the literature and are referred as “Giant epidermal cysts.” Epidermal cysts although common, can mimic other common benign lesions in the head and neck area. A thorough clinico-pathologic investigation is needed to diagnose these cutaneous lesions as they differ in their biologic behavior, treatment, and prognosis. We report a case of a giant epidermoid cyst in the scalp area of a young female patient which mimicked lipoma on clinical, as well as cyotological examination. We also present a brief review of epidermal cysts, their histopathological differential diagnosis, and their malignant transformation.

Trichilemmal cyst of the penis in a paediatric patient

Paediatric penile cysts are uncommon. We report a five-year-old child with an asymptomatic progressively growing cyst on the ventral aspect of the penis after a hypospadias repair. The patient presented to the Cooper Health Clinic, Dubai, United Arab Emirates, in March 2012. A complete excision of the cyst was performed. Histology results delineated a capsulated benign trichilemmal cyst. No recurrence or complications were reported in the 26 months following the excision. We recommend an early and complete excision of all penile cysts to prevent the risk of urethral obstruction, infection, inflammation and rare malignant changes. This is the first reported case of a penile trichilemmal cyst in a child.