Could EMA and cytokeratin 7 be useful in distinguishing tricholemmal carcinoma from clear-cell squamous cell carcinoma? A case series from our department and a brief review of the literature

A Frequent Diagnostic Pitfall: Dermatological Clinical Features and Pathological Results in Diagnosing Pagetoid Squamous Cell Carcinoma in situ (Case Series)

Squamous cell carcinoma (SCC) in situ can occur on any skin or mucus surface and is more commonly found in elderly patients on areas of skin that have been sunburnt. Most previous case reports are from dermatologists, with few published reports from pathologists. In this study, three patients underwent pathological routine and auxiliary immunohistochemical (IHC) examination and were ultimately diagnosed with pagetoid SCC in situ - a different diagnosis from the initial clinical assessment. All three patients received a complete resection of the skin mass. After follow-up, as of June 2023, the patients had no tumour recurrence or metastasis. Pagetoid SCC in situ is a particular type of SCC in situ that has no specific features in clinical manifestations, gross diagnosis or histopathological sections. The final diagnosis depends on IHC staining. Pagetoid SCC in situ expresses EMA, CK5/6 and p63 but not CEA, CK8 or S-100, which are expressed in extramammary Paget's disease. Pagetoid SCC in situ is usually only locally invasive, and the main treatment is complete surgical resection. The prognosis is related to human papillomavirus infection, surgical margin closure, disease location, tumour thickness and other factors.

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.

Cutaneous tricholemmal carcinoma: a 15-year single center experience

BACKGROUND

Clear cell morphology has been described in several cutaneous neoplasms either as a specific feature of some entities either as a morphological variant in the spectrum, and these two entities are frequently considered together in the differential diagnosis.

METHODS

We reviewed our series of cases occurred in our laboratory in order to further quantify the number of cases showing morphological features of tricholemmal differentiation and to investigate other clinical or histological difference. We retrieved 91 cases and, for each of them, all the clinical data regarding age, sex, clinical features, and clinical suspicious were collected, when available.

RESULTS

The revision of the specimens concluded with a final diagnosis of tricholemmal carcinoma in 15 cases (17%), all the other cases were thus considered as squamous cell carcinoma with clear cell features. No statistically significant correlations were observed with the demografic or clinicopatholagical parameters such as age, sex or dimensions, but morphological revision highlighted a potentially greater "vertical" growth frequently not matched by a concomitant radial one in tricholemmal carcinoma than in squamous tumors.

CONCLUSIONS

The debate upon the diagnostic distinction of these tumors is still ongoing with authors proposing the tricholemmal carcinoma as a variant of a squamous cell carcinoma rather than a distinct entity. Further studies are needed to confirm our data and to evaluate the reproducibility of this feature.

A previously undescribed variant of cutaneous clear-cell squamous cell carcinoma with psammomatous calcification and intratumoral giant cell granulomas

Cutaneous clear-cell squamous cell carcinoma (ccSCC) is a rare variant of SCC composed of clear cells that lack cytoplasmic glycogen or evidence of tricholemmal keratinization. We report a previously undescribed variant of ccSCC with psammomatous calcification and intratumoral giant cell granulomas. The differential diagnosis with trichilemmal carcinoma is outlined according to the criteria of the fourth edition of World Health Organization (WHO) classification. Our findings outline that psammomatous calcification may occur inside the keratinous pearls of the neoplastic lobules triggering an intratumoral giant cell granulomatous reaction. The prognostic significance of this histopathological presentation is unknown but the potential for formation of psammoma bodies in cSCC should be considered to avoid diagnostic pitfalls.