Low-grade malignant proliferating pilar tumor simulating a squamous-cell carcinoma in an elderly female: a case report and immunohistochemical study

Malignant Proliferating Pilar Tumor: Clinicopathologic, Immunohistochemical, and Molecular Study of 17 Cases

Proliferating pilar tumors are rare neoplasms that differentiate toward the outer sheath near the isthmus and can rarely undergo malignant transformation. We performed histopathologic evaluation on 26 benign proliferating pilar tumor (BPPT) and 17 malignant proliferating pilar tumor (MPPT). Ki-67 and p53 immunostains were performed on 13 BPPT and 10 MPPT. Six MPPT cases were successfully analyzed by a next-generation sequencing platform which surveyed exonic DNA sequences of 447 cancer genes and 191 regions across 60 genes for rearrangement detection. Patient demographics and clinical characteristics were similar between the BPPT and MPPT groups. Follow-up data of 16 of 17 MPPT (median, 25 mo) showed metastasis in 1 MPPT. The histologic features associated with MPPT include size >2.5 cm, adjacent desmoplastic stroma, small nests or cords of atypical epithelium in surrounding stroma, irregular infiltration or borders, abnormal keratinization, large hyperchromatic nuclei, prominent nucleoli, severe cytologic atypia, nuclear pleomorphism, necrosis, and increased mitotic figures. MPPT harbors copy number gains of 15q and losses of 6p and 6q, findings previously reported in BPPT. However, MPPT harbors frequent TP53 mutations as molecular markers of progression. Different from cutaneous squamous cell carcinoma, MPPT more frequently demonstrates low tumor mutational burden and typically lacks a UV signature, suggestive of a different etiologic pathway than squamous cell carcinoma. In summary, with a median follow-up of 25 months, this study shows that MPPT is a biologically indolent carcinoma with rare metastasis. Molecular analyses suggest a non-UV-related pathogenesis with frequent TP53 aberration.

Proliferating Pilar Tumors Are Characterized by Recurrent 15q, 6q, and 6p22.2 Alterations

ABSTRACT

Proliferating pilar tumors (PPTs) are rare neoplasms of external root sheath derivation, which most commonly occur on the scalp of elderly women. Although typically showing classic histologic features such as trichilemmal type keratinization, a lobular architecture and peripheral palisading, squamous cell carcinoma (SCC) remains a common diagnostic pitfall. Therefore, we sought to explore the molecular pathogenesis of PPTs and compare it with that of cutaneous squamous cell carcinoma (cSCC). Herein, we describe the use of a next-generation DNA sequencing platform to provide the most comprehensive molecular genetic analysis to date of a cohort of 5 PPTs and compare them to 5 head and neck cutaneous SCCs. Recurrent broad arm-level gains of 15q and concurrent single-copy losses of 6q and 6p22.2 were observed in 4 of 5 (80%) PPT cases. Other recurrent mutations or alterations of significance were not found in PPTs. Notably, these chromosomal changes were not identified in any of the 5 cutaneous SCCs, which instead showed recurrent alterations in the known SCC driver genes TP53 , CDKN2A , and NOTCH1 . Here, we show for the first time that PPTs are molecularly distinct from cutaneous SCC and provide evidence that recurrent alterations in chromosome 15 and chromosome 6 are central to the pathogenesis of PPTs.

Systematic analysis and case series of the diagnosis and management of trichilemmal carcinoma

Background

Trichilemmal carcinoma (TLC) is a rare malignant cutaneous adnexal neoplasm, with no relatively comprehensive research.

Objective

The aim of this study is to perform an updated statistical analysis so as to better understand TLC's epidemiology, clinical features, diagnosis, and treatment.

Methods

The diagnosis and treatment of three TLC cases in our department were summarized. Then, all TLC cases published in the literature were retrieved for a comprehensive analysis, followed by the analysis of global trends and regional distribution, demographic characteristics, clinical features, pathogenesis, histopathological features, and treatment and prognosis of TLC.

Results

Of the 231 cases, the incidence of TLC has shown an upward trend recently, especially in China, in Asia. The susceptible population is men aged 60-80 and women over 80, and the most prone location is head and neck. The phenotype of TLC is not always typical and may be misdiagnosed because of the coexistence of other diseases. There is a linear relationship between the diameter and its duration or thickness. UV, locally present skin lesions, trauma, scarring, organ transplantation, and genetic disorders may trigger the occurrence of TLC. Periodic acid-Schiff staining and CD34, but not Epithelial Membrane Antigen (EMA), were helpful in the diagnosis of TLC. Although effective, surgical excision and Mohs micrographic surgery need further improvement to reduce recurrence of TLC. Carcinoma history is an independent risk factor for TLC recurrence.

Limitations

The limitation of this study is the lack of randomized controlled trial on TLC treatment and recurrence.

Conclusion

TLC has the possibility of invasive growth and recurrence, especially in patients with longer duration and carcinoma history.

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.

Malignant Proliferating Trichilemmal Tumor of the Scalp: A Systematic Review

OBJECTIVES

Malignant proliferating trichilemmal tumors of the scalp can exhibit aggressive presentation and recurrences. Our objective was to perform an evidence-based systematic review evaluating clinical presentation, tumor characteristics, and treatment modalities used to determine which treatment strategies had the best outcomes.

METHODS

The databases PubMed, Embase, and Cochrane Library were searched for relevant literature by the authors. Patient demographics, imaging, treatments, and other clinical characteristics were obtained. The results were reported using the Preferred Reporting Systems for Systematic Reviews and Meta-Analysis guidelines.

RESULTS

Thirty-nine studies with a total of 65 patients were identified. The most common presentation was a history of slow-growing, painless swollen mass on the scalp. In total, 10 patients (15.4%) presented with spread to the regional lymph nodes and 6 (9.2%) additional patients presented with metastasis to distant locations. In total, 61 patients (93.8%) underwent surgery. Various chemotherapy and radiation therapy regimens were used. Of the 45 cases with documented follow-up, 11 (24.4%) patients had one or multiple instances of local, lymph node or metastatic tumor recurrence.

CONCLUSIONS

Surgery is favored, and the exact approach should be based on clinical judgment. However, Mohs micrographic surgery should strongly be considered because of its superior margin control against such an invasive tumor. Radiotherapy and chemotherapy have been used as adjuvant therapy in aggressive cases or recurrence. Patients should be followed closely and examined often to frequently assess recurrence or metastasis. Randomized controlled trials are needed to further clarify these findings.

Malignant Proliferating Trichilemmal Tumor: A Subtle Presentation in an African American Woman and Review of Immunohistochemical Markers for This Rare Condition

A malignant proliferating trichilemmal tumor (MPTT) is thought to represent the malignant counterpart of a benign proliferating trichilemmal cyst, a keratin-filled lesion that derives from the outer hair root sheath. The clinical appearance of MPTTs does not always correlate with their histopathologic behavior, emphasizing the need for biopsy and histopathological analysis. Here, we present a 46-year-old African American woman who was evaluated for an ostensibly benign cyst on her scalp that was diagnosed as an MPTT following histopathological examination. She was treated with simple surgical resection that was flush with the cyst margins, followed by Mohs surgery to ensure complete resection. As immunohistochemistry (IHC) has often been used to characterize MPTTs, we also review the various IHC markers reported in the literature.

Proliferating Pilar Tumors: Can Immunohistochemistry Differentiate Benign and Malignant Forms?

BACKGROUND

Proliferating pilar tumor (PPT) is an adnexal tumor of purported differentiation toward the follicular outer root sheath. Immunohistochemistry has been suggested to differentiate between benign and malignant forms.

METHODS

Eleven benign (PPT) and 9 malignant PPT lesions were reviewed; Ki67, p27, and p53 were applied. The staining intensity (strong, moderate, weak, and negative), positive cell numbers, and marker indexes (%) were scored using image-analysis software (ViraSoft).

RESULTS

Overall, there was no significant correlation between Ki67 and p53 and histopathological features. However, malignant PPTs had significantly lower numbers of p27-positive cells (P = 0.030).

CONCLUSIONS

Our study includes the largest group of patients in whom image analysis of p53, Ki67, and p27 has been used to try to separate benign from malignant lesions. Although there were no significant differences regarding Ki67 and p53, malignant lesions have a statistically lower expression of p27. Further studies may be needed to determine the clinical usefulness of image analysis in this differential diagnosis.

Diagnostic value of CD34 and calretinin immunostaining in the diagnosis of proliferating tricholemmal tumor and trichoblastoma

BACKGROUND

Proliferating tricholemmal tumor (PTT) is a rare neoplasm of controversial biological behavior for which distinction from other more common tumors is essential. Similarly, trichoblastoma (TB) remains a debatable entity that may represent a variation of basal cell carcinoma (BCC). Our goal is to correlate the staining pattern of calretinin and CD34 in these two follicular tumors vs. their major differential diagnoses, invasive squamous cell carcinoma (ISCC) and BCC.

METHOD

Descriptive study of 68 cases: 6 PTT, 22 TB, 20 ISCC, and 20 BCC in a period of 15 years. The diagnosis was confirmed with H&E. The immunohistochemistry results were analyzed and scored positive (weak +, moderate ++, and strong +++) or negative.

RESULTS

Calretinin was expressed in 4/6 cases of PTT and negative in all TB. Only one malignant case of PTT was positive for CD34 (1/2) and negative in all TB cases. Calretinin and CD34 were negative for all ISCC and BCC. The intensities are shown in tables.

CONCLUSION

The diagnosis of these neoplasms is a morphologic diagnosis. However, in those cases where the morphologic aspect is difficult to interpret, calretinin may assist in the diagnosis of PTT, distinguishing the hair follicle tumors with an outer root sheath differentiation. Likewise, CD34 showed significant affinity for the malignant subset of PTT. Calretinin and CD34 did not add any value to the differentiation between TB and BCC. However, this might suggest that both are the same entity with a different morphological permutation.

A proliferating trichilemmal cyst in the perianal region: A case report

INTRODUCTION

Proliferating trichilemmal cysts (PTCs) are rare benign neoplasms originating from the follicular isthmus. They can undergo trichilemmal keratinization and malignant degeneration to form epidermoid carcinoma. They occur on the scalp in more than 90% of patients and are more common in elderly women.

PRESENTATION OF CASE

A 56-year-old woman complained of perianal discomfort upon sitting. She presented with a perianal nodule of approximately 3 cm in diameter that had exhibited slow and progressive growth over 8 years. After surgical excision of the lesion with safety margins, histopathological examination showed that it was a proliferating trichilemmal cyst in the perianal region.

DISCUSSION

There are no reports in the literature on PTC in the perianal region. The location with the highest prevalence is the scalp; other sites of occurrence are the neck, trunk, underarms, pubis, vulva, lower and upper limbs, upper lip, and gluteal region.

CONCLUSION

The development of PTC in the perianal region is an exceptional occurrence, and when it does occur, surgical treatment should always be indicated because of the risk of malignant degeneration to form epidermoid carcinoma.

Extensive and ulcerated malignant proliferating trichilemmal (pilar) tumour, arising from multiple, large, degenerated trichilemmal (pilar) cysts

We report a rare case of a 61-year-old homeless man with a 15-year history of multiple trichilemmal cysts that served as a forerunner for the emergence of a malignant proliferating pilar tumour. The patient presented multiple, large, purulent, ulcerated lesions ranging from 10 to 150 mm in diameter, covering most of the scalp, with large areas superimposed by extensive myiasis infestation. The patient presented with no other major clinical findings. A CT scan showed no detectable signs of local or distant metastatic invasion. Initial supportive treatment was implemented. Given the extent of the injury, further surgical excision was considered, which required transfer to a specialised surgical centre. This social case is of educational value, as it can raise clinician awareness about the ability of trichilemmal cysts to undergo malignant transformation. Additionally, it highlights the importance of adequate social assistance structures for patients in need.

A Rare Cutaneous Adnexal Tumor: Malignant Proliferating Trichilemmal Tumor

Proliferating trichilemmal tumors (PTTs) are neoplasms derived from the outer root sheath of the hair follicle. These tumors, which commonly affect the scalp of elderly women, rarely demonstrate malignant transformation. Although invasion of the tumors into neighboring tissues and being accompanied with anaplasia and necrosis are accepted as findings of malignancy, histological features may not always be sufficient to identify these tumors. The clinical behavior of the tumor may be incompatible with its histological characteristics. Squamous-cell carcinoma should certainly be considered in differential diagnosis because of its similarity in morphological appearance with PTT. Immunostaining for CD34, P53, and Ki-67 is a useful adjuvant diagnostic method that can be used in differential diagnosis aside from morphological findings. In this study, we aimed to present the case of a 52-year-old female patient with clinicopathological features. We reported a low-grade malignant proliferating trichilemmal tumor in this patient and detected no relapse or metastasis in a 24-month period of follow-up.