Hair Matrix Differentiation Research Articles

Melanocytic Matricoma With Atypical Histopathological Features: A Case Report of an Extremely Rare Entity and Review of the Literature.

Melanocytic matricoma with atypical features is a rare, biphasic adnexal neoplasm displaying hair matrix differentiation, with only 3 reported cases worldwide. Generally, the lesion comprised a solid matrical and supramatrical cell proliferation, admixed with intermediate cell aggregates with sparse anucleated "shadow cells" and a prominent pigmented melanocytic hyperplasia. We report the case of a 78-year-old man with a slow-growing crusted lesion on the frontal left scalp, which in a matter of 1-2 months became a 0.6 cm well-defined, black purplish exophytic nodule. Histopathologically, the lesion presented a well-circumscribed border with a nodular dermal growth pattern, presenting different architectural features varying from benign pilomatricoma-like changes to atypical features such as moderate-to-high nuclear pleomorphism in both basaloid (matrical/supramatrical) and epidermal (keratinous) components. Strong nuclear and cytoplasmic positivity for β-catenin was observed in matrical cells, whereas prominent cytoplasmic membrane positivity for Melan-A in dendritic melanocytes. Owing to the evidence of atypical cytological features, we propose the "atypical/borderline" category of melanocytic matricoma as part of a possible spectrum among matrical neoplasms. Pathologists should be aware of any atypical histopathological features while reporting cases due to their potential malignant transformation.

Pilomatricoma: A tumor with hidden depths

Pilomatricoma is a benign tumor of hair matrix differentiation and has been classically described as comprising of basaloid and shadow cells admixed with multinucleated giant cells and areas of calcification. However, there are a diverse range of histologic features this tumor displays that are often unrecognized. This study was undertaken to record the histopathologic features of pilomatricoma with an emphasis on the occurrence of other forms of differentiation. The study included all skin biopsy specimens over a 13-year period from 1995 to 2007 that had a histologic diagnosis of pilomatricoma. Hematoxylin and eosin-stained slides were reviewed. This study included 21 cases of pilomatricoma. Supramatrical differentiation was seen in all cases and three-quarters of the cases showed matrical differentiation. Also observed in some of the cases were clear cell differentiation toward the outer root sheath, infundibular differentiation, calcification, ossification and secondary inflammation with a foreign body giant cell reaction. Epidermal induction in the form of a downward plate-like growth of the epidermis was seen in a few cases. Pilomatricoma, although considered a tumor of hair matrix differentiation, can show cellular evolution toward the other parts of the hair follicle, such as the outer and inner root sheaths, sebaceous and infundibular components and, therefore, can be considered a panfollicular neoplasm.

Proliferating pilomatricoma: a subset of pilomatricoma

Proliferating pilomatricoma is a histopathological entity that was proposed by Kaddu et al. in 1997. Proliferating pilomatricoma represents a distinctive histopathological entity; it should be differentiated from other benign and malignant neoplasms with features of hair matrix differentiation. Kaddu reported that an incompletely excised proliferating pilomatricoma may have a greater potential for local recurrence, because histopathologically it showed variable nuclear atypia and several mitotic figures. We report two patients with proliferating pilomatricoma and describe their clinical and pathological features.

Basal cell carcinoma with matrical differentiation in a transplant patient: A case report and review of the literature

Shadow cells, characterized by basaloid squamous cells with a distinct well-defined border and a central unstained area as a shadow of lost nuclei, are characteristic of pilomatricoma, a distinct neoplasm of hair matrix differentiation. The presence of shadow cells within tumor islands composed of follicular germinative cells of an otherwise classic basal cell carcinoma (BCC) has been considered as a distinct diagnostic category of BCC with matrical differentiation. We present a case of BCC with matrical differentiation in a transplant patient. To our knowledge, only 10 cases [Aloi et al. Am J Dermatopathol 1988; 10: 509; Ambrojo et al. Am J Dermatopathol 1992; 14: 293; Sagol et al. East J Med 1999; 4: 37; Kwittken J. Cutis 2002; 69: 57; Kim et al. Yonsei Med J 2003; 44: 523] of BCC showing matrical differentiation have been reported. None have been reported arising on the background of immunosuppression. A 58-year-old male cardiac transplant patient with a nodule on the dorsum of left hand was studied. It arose and enlarged rapidly within a few months, causing irritation and bleeding. The nodule was surgically excised and submitted for histopathologic evaluation. The sections were prepared by hematoxylin and eosin (H&E) method. The H&E-stained sections of the hand lesion revealed multiple nodular masses of basaloid follicular germinative cells. In some areas, there was peripheral palisading and stromal retraction artifact typical of classic BCC. In these areas, the tumor nodules were connected to the epidermis, whereas in others, it extended deep into the reticular dermis to the subcutaneous fat junction. Elsewhere, the majority of the tumor contained a population of shadow cells, similar to those in pilomatricoma, with basaloid-appearing matrical cells in the periphery. Trichohyaline granules were identified in the cytoplasm of many of the peripheral basaloid cells. These granules are one of the characteristic features of follicular matrix differentiation. Mitoses were rare. Areas of cystic degeneration were present throughout the tumor. There was no evidence of an infiltrating growth pattern, lymphovascular invasion, or sarcomatoid growth pattern. BCC with matrical differentiation is a distinct pathologic entity and a rare subtype of BCC featuring shadow and matrical cells, typically seen in pilomatricoma, a benign hair matrix neoplasm. This tumor has not yet been reported in an immunosuppressed transplant patient.

Basal cell carcinoma with matrical differentiation: a case study with analysis of β‐catenin*

Matrical differentiation in basal cell carcinoma (BCC) is rare. Only nine cases have been described that showed typical diagnostic features of BCC, in addition to shadow cells indicating hair-matrix differentiation. These cases often present a diagnostic challenge due to confusion with pilomatrixoma or pilomatrix carcinoma. We present a case of BCC with matrical differentiation in a 78-year-old man. Immunohistochemical and molecular methods are used to differentiate this lesion from benign or malignant forms of pilomatrixoma. differentiation: a case study with analysis of beta-catenin.

Hair Matrix Differentiation in a Trichogenic Adnexal Neoplasm.

Pilomatricoma is a distinctive tumor characterized by a dual population of proliferating germinative cells and shadow cells and is beleived to derive from the hair matrix. Rarely, benign and malignant adnexal tumors can show pilomaticoma‐like or hair matrix differentiation. We present a 69‐year‐old man with a ruptured cystic nodule of the left cheek. Histology revealed a dermal tumor composed of nests of basaloid cells which manifested peripheral palisading and abortive hair papilla formation with a modified stroma and pilomatricoma‐like areas. This lesion shares features of a trichogenic adnexal neoplasm with those of a tumor having hair matrical differentiation, and has been rarely reported under the designation “follicular” basal cell carcinoma (BCC). This case illustrates an example of this unusual occurrence of hair matrix differentiation in a benign basaloid adnexal neoplasm as characterized by the presence of basaloid and shadow cells; the absence of individual cell necrosis and mitotic activity prompts us to doubt that it represents a form of nodular BCC, but rather it more likely reflects a hamartoma of the follicular anlage.

Basal Cell Carcinoma With Matrical Differentiation in a Transplant Patient: A Case Report and Review of the Literature

Background: Shadow cells are characteristic of pilomatricoma, a distinct neoplasm of hair matrix differentiation. Shadow cells within an otherwise classic basal cell carcinoma (BCC) has been referred to as “BCC with matrical differentiation”. We present a case of BCC with matrical differentiation in a transplant patient. To our knowledge, none have been reported arising on the background of immunosuppression. Methods: A 58‐year‐old male cardiac transplant patient had a left hand nodule, which was excised and submitted for routine histologic review. Results: The lesion revealed multiple basaloid tumor masses. In some areas, there was peripheral palisading with stromal retraction artifact, typical of basal cell carcinoma, extending into the deep reticular dermis. The tumor also contained a population of shadow cells, similar to those in pilomatricoma, with basaloid cells in the periphery. Trichohyaline granules were identified in many of the tumor cells. These granules are a hallmark of follicular matrix differentiation. Mitoses were rare. There was no evidence of an infiltrating growth pattern. Conclusion: Basal cell carcinoma with matrical differentiation is a rare subtype of basal cell carcinoma featuring shadow cells, such as those typically seen in pilomatricoma. This tumor has not yet been reported in an immunosuppressed transplant patient.

Pilomatrix carcinoma and multiple pilomatrixomas

Pilomatrixoma is the only skin appendage tumour showing predominantly hair matrix differentiation. Rarely, aggressive or malignant variants are reported in the literature. We report a case of a 44-year-old male with multiple pilomatrixomas, one of which grew rapidly, recurring several times. Histological examination of this tumour showed predominantly hair matrix differentiation but also abortive hair follicle formation with pilar keratinization reminiscent of a trichoepithelioma. Numerous mitoses and moderate cellular pleomorphism were present, associated with infiltration of subcutaneous skeletal muscle and vascular invasion.

Hair Matrix Differentiation

The formation of structures resembling hair matrices is the least common form of follicular differentiation and only occurs with any frequency in pilomatricoma. Rarely, follicular cysts and both benign and malignant adnexal tumors can show areas of pilomatricoma-like change, or hair matrix differentiation. Examples of focal hair matrix differentiation in a follicular cyst, a cutaneous mixed tumor, and an adnexal carcinoma are presented. Each of these cases also demonstrates the presence of limited differentiation toward structures of the inner root sheath.