A Rare Cutaneous Adnexal Tumor: Malignant Proliferating Trichilemmal Tumor

Abstract

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.

Atypical Proliferating Trichilemmal Cyst with Malignant Breast Skin Transformation: A Case Report and Review of the Literature

“…A stepwise transformation of MPTTs has been described from an adenomatous to an epitheliomatous and then to a carcinomatous stage [ 11 ]. Additionally, in a study in which 76 patients were evaluated, the clinicopathological categorization of PTTs into three groups was proposed [ 4 , 7 ].…”

“…Even though the diagnosis of MPTTs is mostly done in a histopathological fashion, the use of immunohistochemistry can help to distinguish MPTTs from PTTs and SCCs. CD34 is a marker that is closely associated with trichilemmal keratinization, and because it is absent in SCCs and present in MPTTs it can help in differentiating one condition from the other (an important distinction because MPTTs have a greater chance of recurring and metastasizing) [ 7 , 12 ]. As with this case, there have been reports of MPTTs where a negative staining with CD34 is observed.…”

“…Moreover, some authors have postulated that a loss of CD34 staining is related to a decrease in the differentiation of the tumor. Ki-67 and p53 can help in the distinction of MPTTs from PTTs, as both markers are usually absent or dimly expressed in PTTs [ 7 ].…”

“…Additionally, most of the patients that present these lesions are elderly women, and in 90% of the cases these tumors occur on the scalp [ 4 ]. PTTs rarely exhibit malignant transformation (characterized by invading neighboring tissues and the presence of anaplasia and necrosis) into malignant proliferating trichilemmal tumors (MPTTs) [ 5 – 7 ], a fact substantiated by the presence of less than 50 cases of MPTTs reported in the English medical literature.…”

Infections, Infestations and Neoplasms of the Scalp

“…Complete excision is recommended for the treatment of PCT owing to their potential for locally aggressive behaviour and malignant transformation [81,83]. If malignant PTC with multi-nodal metastasis is identified, wide local excision with 1-cm margins should be performed, followed by adjuvant chemotherapy and radiation to prevent recurrence [84].…”