Eruptive Vellus Hair Cyst: An Uncommon and Underdiagnosed Entity

A Facial Solitary Vellus Hair Cyst: A Rare Entity

This case report details a rare occurrence of a vellus hair cyst presenting as a recurrent nodular swelling on the medial aspect of the right eye in a 23-year-old male. The patient underwent surgical excision guided by imaging studies, and the subsequent two-month follow-up revealed no signs of recurrence. Imaging, including contrast-enhanced computer tomography (CECT), played a crucial role in assessing the extent of the lesion and ruling out intracranial involvement. Histopathological examination confirmed the diagnosis, revealing cystic spaces with an attenuated lining containing vellus hair and marked fibrosis. The case underscores the importance of considering uncommon entities in differential diagnoses, emphasizes the efficacy of complete cyst removal in preventing recurrence, and contributes to the evolving understanding of vellus hair cysts. Further research is warranted to enhance our knowledge of their epidemiology and optimal management strategies.

[Main Types of Cysts in Dermatopathology: Part 1]

Cystic structures represent one of the most common findings in dermatopathology. These encompass both cystic tumors and pseudocysts resulting from the accumulation of certain substances, such as mucin. In a two-part series (of which this is the first part), we have reviewed the principal types of cysts and pseudocysts that may be observed in cutaneous biopsies, examining their histopathological features and primary differential diagnoses. This first part encompasses infundibular cysts, eruptive dermoid cysts, pigmented follicular cysts, pilonidal cysts, tricholemmal cysts, milium cysts, hybrid cysts, bronchogenic cysts, as well as steatocystoma, hydrocystoma, and comedones.

Benign Cutaneous Cysts: A Comprehensive Analysis of 1160 cases

Background Cysts are common skin abnormalities that are mostly benign; however, sometimes malignant lesions may present clinically as cystic manifestations. Benign cutaneous cysts can be of different morphological types and their diagnosis relies on histological evaluations. The most common mode of treatment is surgical excision, which is curative. Methodology This is a retrospective cross-sectional study conducted at the Department of Histopathology, Chughtai Institute of Pathology, Lahore, Pakistan from 1st January 2020 to 31st December 2022. Non-probability consecutive sampling was done, and all the cases of benign cutaneous cysts were included. All cases were microscopically reviewed by two histopathologists, and variables like age, gender, site of the lesion, and histological diagnosis were noted. The data were analyzed using IBM SPSS Statistics for Windows, Version 29 (Released 2022; IBM Corp., Armonk, New York, United States). Results A total of 1160 recorded cases of benign cutaneous cysts were included. Overall gender distribution revealed males (n=489, 42.1%) and females (n=671, 57.8%). The age range was 3 to 91 years with a mean age of 37.56 ± 16.05 years. The three most common cysts were epidermal inclusion cysts (74.3%), trichilemmal cysts (15.1%), and dermoid cysts (6.3%). Other cysts were uncommon including hidrocystoma (1.9%), steatocystoma (0.3%), verrucous cysts (0.3%), comedones (0.6%), hybrid cysts (0.2%), milia (0.3%), and vellus hair cysts (0.2%). The most common site was back (23.5%) for epidermal inclusion cysts, scalp (74.4%) for trichilemmal cysts, and eye (33.8%) for dermoid cysts. Conclusion Benign cutaneous cysts have a broad morphological spectrum with a wide age range. Epidermal inclusion cysts, trichilemmal cysts, dermoid cysts, and hidrocystoma account for the four most common types. For each of the other cyst type, the prevalence was under 1%. Female gender predominated in epidermal inclusion cysts, trichilemmal cysts, and dermoid cysts while male gender was common in other cysts. Overall majority of the cysts presented in the head and neck area.

Eruptive vellus hair cysts: An underdiagnosed entity

Eruptive vellus hair cyst (EVHC) is a rare follicular developmental abnormality of the vellus hair follicles. The usual onset is between 17 and 24 years but may be congenital. It can arise sporadically or may be inherited in an autosomal dominant fashion. They are caused by an abnormality at the infundibular level of vellus hairs. They usually appear as yellow to reddish-brown papules over the chest, limbs, and abdomen. Histologically, cyst has a stratified squamous epithelium and it contains lamellated keratin and several vellus hairs. We present this rare case of a 12-year-old male because of its unusual morphology and distribution and also to generate awareness about this rarely diagnosed condition. To the best of our knowledge, no case of an axillary variant of EVHC has been reported till date.

Mosaic proximal trisomy 13q and regular trisomy 13 in a female patient with long survival: Involvement of an incomplete trisomic rescue and a chromothripsis event

BACKGROUND

Trisomy 13 or Patau syndrome has a prevalence of 1:10,000-20,000 and is characterized by microcephaly, microphthalmia, polydactyly, as well as other dysmorphic features and malformations, with a patient survival of 13% in the first year. Trisomy 13 presents either as a free chromosome 13 trisomy or associated with a chromosomal Robertsonian translocation, as partial trisomy affecting proximal or distal 13q regions, and also as a mosaic. Mosaic trisomy 13 shows a highly variable phenotype, displaying from mild to severe affectations. We present a 12-year-old Mexican female patient with intellectual disability, dysmorphic features, polymenorrhea, and long survival, whose initial cytogenetic study referred to a small supernumerary marker chromosome.

METHODS

GTG banding karyotype, high-resolution chromosomal microarray, and fluorescent in situ hybridization analyses were performed in peripheral blood cells.

RESULTS

Our analyses demonstrated a de novo mosaicism in our patient, constituted by proximal trisomy 13q10-q14.3 (82%) and free trisomy 13 (18%) cell lines. Her final chromosomal complement is mos 47,XX,+del(13)(q14.3)[25]/47,XX,+13[7].ish del(13)(RB1+)[17]/13q14(RB1x3)[2].arr[GRCh37] 13q11q14.3(19436286_51726415)x3,13q11q34(19436286_115107733)x2-3 dn.

CONCLUSIONS

The wide spectrum of clinical manifestations observed in our patient mainly results from the proximal trisomy 13q, and her phenotype is modified by the presence of a free trisomy 13 cell line. We propose that her mosaicism probably derived from a trisomic zygote that underwent a failed trisomic rescue associated with chromothripsis, originating the cell line with partial 13q proximal trisomy, whose selective advantage could explain the long survival of our patient.