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Concept: Trichilemmal cyst


Trichilemmal cyst, also known as “pilar cyst,” is a benign cyst containing keratin and its breakdown products with a wall resembling external root sheath of hair. It occurs mostly in females as a solitary firm nodule over scalp. Occurrence of multiple trichilemmal cysts in areas other than scalp is extremely rare. We are reporting a case of a 40-years-old female who presented with multiple calcified trichilemmal cysts in multicentric distribution associated with alopecia universalis. Similar complaints were present in elder sister of the patient, indicating a genetic background. Multicentric distribution of trichilemmal cysts, calcification, familial occurrence, and association with alopecia universalis seen in our case are all rare and intriguing features.

Concepts: Family, Female, Gamete, Sebaceous cyst, Cyst, Sibling, Trichilemmal cyst


A 53-year-old man presented with smooth-domed, variegated cysts (polycystic disease) of all 4 eyelids, worse on the left side. Some of the cysts were clear, while others were creamy-white colored. In addition, multiple, very fine vesicopapules were noted along the eyelid margins. Histopathologic examination revealed a trichilemmal cyst, several pure apocrine hidrocystomas displaying multiple chambers, a hybrid cyst, and many small eccrine cysts of the deep dermis. The apocrine lesions, including the small ones at the eyelid margins, predominated. Smooth muscle actin sometimes positively stained outer myoepithelial cells in some of the apocrine cysts, which helped to distinguish them from eccrine cysts. Most noteworthy was the fact that the patient had been diagnosed with a prolactinoma 20 years earlier. There is only 1 previous report of multiple apocrine cysts and an antecedent prolactinoma in the dermatologic literature. This syndrome should be separated from that of Schöpf-Schulz-Passarge, which manifests multiple small eyelid apocrine cysts and other ectodermal dysplasias without any association with neoplasia, and from that of focal dermal hypoplasia (Goltz-Gorlin) syndrome with apocrine cysts but again without neoplasia.

Concepts: Anatomical pathology, Actin, Smooth muscle, Dermis, Cyst, Polycystic ovary syndrome, Chalazion, Trichilemmal cyst


Proliferating trichilemmal cyst (PTC) is a rare adnexal tumor, generally benign, primarily sitting on the scalp of elderly women. About fifty cases are reported in the literature. Herein, we describe another one particularly aggressive.

Concepts: Report, Case, Cyst, Trichilemmal cyst


Nevus sebaceus of Jadassohn, a congenital cutaneous hamartoma, has the potential to develop into various epidermal adnexal-origin neoplasms. While the most common neoplasms are trichoblastoma or syringocystadenoma, proliferating trichilemmal cysts are exceptionally rare. We report a case of a 63-year-old Cuban male with a giant proliferating trichilemmal cyst arising from a nevus sebaceus on the right shoulder which had been growing for 30 years. Proliferating trichilemmal cysts arising from nevus sebaceus cases are difficult to diagnose clinically and histologically since they are very rare and have not been defined by exact diagnostic criteria. Our case creates awareness of this particular tumor in nevus sebaceus and shares clinical and histological diagnostic information that can be used to make a proper diagnosis.

Concepts: Cancer, Medical terms, Diagnosis, Anatomical pathology, Greek loanwords, Trichilemmal cyst


Proliferating trichilemmal cyst is considered as a rare tumor that originates in the outer root sheath of hair follicle. Metastatic potential has not been yet fully established. Moreover, histological analysis does not allow precise malignancy prediction. Proliferating trichilemmal cyst glucose metabolism behavior was never previously described. Herein, we report the case of a 62-year-old patient with a left shoulder proliferating trichilemmal cyst showing an intense uptake of F-FDG on PET/CT examination. F-FDG PET/CT could be proposed to optimize diagnostic strategy of patients with proliferating trichilemmal cysts.

Concepts: Protein, Cancer, Oncology, Medical terms, Sebaceous cyst, Cyst, Dermoid cyst, Trichilemmal cyst


Pilar cysts are common squamous-lined cysts that typically occur on the scalp. They are believed to arise from the isthmus of anagen hairs or from the sac surrounding catagen and telogen hairs. The authors describe a rare case of a pilar cyst with prominent ductal differentiation, presumably of eccrine derivation. Sweat duct differentiation has been described in a myriad of cutaneous neoplasms and rarely within epidermoid cysts. The authors could only find one other case in the literature describing a pilar cyst with sebaceous and apocrine differentiation. The clinicopathologic findings are described here.

Concepts: Ovarian cyst, Skin, Sebaceous cyst, Cyst, Hair, Hair follicle, Sebaceous gland, Trichilemmal cyst



Proliferating trichilemmal tumor (PTT) is a rare but morphologically distinct tumor that usually arises on the scalp of elderly women. It is composed of multiple cysts consisting of squamous epithelium with trichilemmal keratinization without granular layer interposition. Vulvar proliferating trichilemmal cyst is very rare, with, to the best of our knowledge, only 3 cases previously reported in the literature. We describe a 39-year-old woman with recurrent PTT on the left labium majus of the vulva, which had been excised from the same side 5 years before. She had a palpable nodule, approximately 2 cm in size, which was firm, mobile, and nontender; without erythema and ulceration; and covered by normal skin on the vulva. There was no inguinal lymphadenopathy. The lesion was removed by wide surgical excision; because of the tissue elasticity, primary closure was possible. The pathology result was reported as proliferating trichilemmal carcinoma with tumor-free margins. Although local recurrence after wide excision is rare, we recommend complete excision for treatment of PTT and long-term follow-up because of the possibility of recurrence.

Concepts: Surgery, Skin, Squamous cell carcinoma, Cyst, Dermoid cyst, Excision, Epidermal nevi, neoplasms, cysts, Trichilemmal cyst