Melanocytic Matricoma Research Articles

Atypical Melanocytic Matricoma: A Case Report with Molecular Studies.

Melanocytic matricoma is a rare benign pilar tumor characterized by matrical differentiation and interspersed dendritic melanocytes. It may show cellular atypia and brisk mitotic activity. Histological characterization of some lesions may be difficult. In addition, because the reported cases are few and have limited follow-up, there is insufficient experience to define outcome-based criteria for malignancy. Some cases of melanocytic matricoma with more prominent atypia have been reported as malignant, but their clinical behavior is uncertain. We present a melanocytic matricoma with interspersed benign dendritic melanocytes, but moderate basaloid atypia, focally brisk mitotic activity, and atypical mitoses. Despite the apparently good delimitation of this tumor, higher magnification revealed a slightly irregular border. However, overt malignant features such as necrosis, frank asymmetry, deep infiltration, and ulceration were not present. This tumor showed a complex aberrant genomic profile with multiple whole chromosomes or chromosomal arms, losses, and duplications. The tumor mutational burden was high. A loss-of-function alteration in CDKN2A and a loss-of-function mutation in TP53 were also present. This unexpected molecular profile contrasts with the relatively bland histology of the tumor and is in line with the difficulties in microscopic differential diagnosis between melanocytic matricoma and an indolent malignant pilomatrical tumor. We suggest that molecular studies and longer follow-up periods may help to further understand and more precisely categorize borderline pilomatrical tumors with melanocytic hyperplasia.

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.

Melanocytic matricoma: a rare tumor that can mimic melanoma

Melanocytic matricoma: a rare tumor that can mimic melanoma

Melanocytic matricoma: A new case with literature review

Melanocytic matricoma: A new case with literature review

Malignant Melanocytic Matricoma and Criteria for Malignancy

Melanocytic matricoma is a very rare adnexal tumor that recapitulates the anagen hair follicle bulb. Few cases of malignant melanocytic matricoma have been reported, thus criteria for malignant potential have not been previously reviewed. We report a case of an 81 year old male that was originally diagnosed as atypical melanocytic matricoma. The site was re-excised with a small focus of residual tumor, but all margins were negative. The re-excision site healed without complication. However, two years after the original biopsy, a new 8 mm firm nodule appeared at the re-excision site, which was subsequently diagnosed as malignant melanocytic matricoma (MMM). In the following paper we will report a new case of MMM and review potential criteria that could be used in the future to establish malignant potential.

Melanocytic matricoma: an additional case with literature review over this rare entity

Melanocytic matricoma: an additional case with literature review over this rare entity

Melanocytic matricoma: two cases of a rare entity in women

Melanocytic matricoma is a rare cutaneous adnexal tumor occurring in humans with only 13 cases reported in the literature. The typical lesion is a circumscribed pigmented nodule on sun-damaged skin. Most cases have occurred in elderly men. The tumor contains a mixed population of matrical cells, supramatrical cells, shadow or ghost cells, and dendritic melanocytes. We report two cases of melanocytic matricoma in two elderly women with unusual histopathological features such as cystic degeneration and focal granulomatous inflammation, which are considered to be atypical for this entity.

Locally Invasive Dermal Squamomelanocytic Tumor With Matrical Differentiation

Dermal-based combined squamous and melanocytic neoplasms are emerging clinicopathologic entities that tend to appear on sun-exposed areas of elderly patients. The biologic behavior of such cutaneous neoplasms remains uncertain because of their rarity. Histopathologic differential includes the following diagnostic entities: (1) dermal squamomelanocytic tumor, (2) melanocytic matricoma, and (3) rare histologic variant of pilomatrical carcinoma, the so-called pilomatrical carcinoma with intralesional melanocytes. Herein, we present a novel case of locally invasive dermal squamomelanocytic tumor. A 72-year-old man presented with a pigmented papule on nasal ala that was clinically concerning for basal cell carcinoma. Histopathologic evaluation demonstrated atypical melanocytic cells architecturally and intimately intermixed with single units and clusters of atypical squamous cells. Most notable feature of this case is focal matrical differentiation and locally invasive tumor growth, characterized by multifocal perineural invasion.

Malignant melanocytic matricoma: a case report and review of the literature

Aim To describe and review literatures for malignant melanocytic matricoma and, to discuss the differentials and potential diagnostic pitfalls. Method A skin excision from an 81-year-old man presenting with a skin lesion was processed routinely and examined, including several immunohistochemical studies, namely AE1/AE3, S-100, and MelanA. Result The tumour was characterised by an exophytic nodular growth with ulceration displaying biphasic features, and composed of both basaloid cells and larger pigmented melanocytic cells. Pigmentation was variable, with dendritic cells noted. Up to 20 mitoses/10 HPF were observed. The small basaloid tumour cells were positive for AE1/AE3, and the larger tumour cells were positive for S-100 and MelanA. Discussion This entity is a malignant neoplasm with hair matrix and hair differentiation. The histological criteria in favour of malignancy include infiltrative growth, numerous mitotic figures, abnormal mitoses, nuclear atypia, loss of ghost cells at the advancing edge, lymphatic and blood vessel invasion, perineural invasion, local recurrence and lymph node or visceral metastases.

Melanocytic Matricoma With Melanocytic Atypia: Report of a Unique Case and Review of the Literature

Melanocytic matricoma is a rare cutaneous neoplasm of presumed anagen hair follicle origin with approximately 10 reported cases in the literature. Melanocytic matricomas are clinically and histopathologically distinct cutaneous nodular proliferations of matrical and supramatrical cells admixed with dendritic melanocytes, which typically occur in the sun-exposed areas of elderly patients. We report a new case with additional histopathologic features not previously described. An 82-year-old white man presented with an exophytic papule of the ear clinically suspicious for basal cell carcinoma. Histopathologic examination demonstrated a polypoid neoplasm consisting of an admixture of matrical and shadow cells with numerous interspersed dendritic and epithelioid melanocytes arranged singly and in large expansile nests. An unusual feature in this case included prominent melanocytic proliferation with associated nuclear atypia and increased mitotic activity. Although atypical and malignant melanocytic colonization has been reported in basal cell carcinomas and squamoproliferative lesions, to our knowledge, it has not been previously described in melanocytic matricomas. The biologic significance of atypical melanocytic proliferations within melanocytic matricomas is uncertain and requires further study of additional cases and long-term follow-up.

Where Pigmented Pilomatricoma and Melanocytic Matricoma Collide

Pilomatricoma and matricoma are 2 benign epithelial tumours derived from the hair matrix. Although containing the same constituent cells, the silhouette differs, with matricoma comprised of a predominantly solid basaloid proliferation with only focal areas of shadow cell formation. The recently described melanocytic matricoma appears to be a similar tumor with numerous interspersed melanocytes. We studied retrospectively 28 pilomatricomas and 2 pilomatrical carcinomas to check for the presence of melanocytes using immunohistochemical staining to S-100 and Melan-A. Three cases of pilomatricoma with prominent melanocytic hyperplasia were detected, confirming this as a rare (11%) occurrence. Both cases of pilomatrical carcinoma were negative. Comparison of these tumors with a further case of melanocytic matricoma led to a critical analysis of the relationship of pilomatricoma, matricoma, and melanocytic matricoma. Although further comparison is required, we suggest that melanocytic matricoma may be simply a pigmented melanocytic variant of matricoma, in the same way as we accept pigmented pilomatricoma as a variant of pilomatricoma. In this report we provide features that may be used to discriminate matricoma and pilomatricoma and their pigmented variants.

Melanocytic matricoma. Report of a further case with clinicopathological and immunohistochemical findings, differential diagnosis and review of the literature.

Melanocytic matricoma is a rare recently described lesion. It usually presents as a pigmented, dark-papular, crusted lesion on sun-damaged skin of adult patients. Histopathologically, these lesions are characterized by well-circumscribed nodules composed of matrical and supramatrical cells with clustered shadow cells, and admixed pigmented dendritic melanocytes. It differs from matricomas and pilomatricomas by its lack of calcification, cyst formation, granulomas, and connections to the epidermis and other adnexal structures. The clinical differential diagnosis includes hemangioma, pigmented basal cell carcinoma, and melanoma. Melanocytic matricoma presumably is the representation of an epithelial-melanocytic interaction in the anagen phase of the hair cycle. An extensive search of the medical literature revealed 11 reports of benign melanocytic matricomas and 5 malignant counterparts. We report an additional case of melanocytic matricoma with discussion of clinicopathologic features and differential diagnosis.

Squamomelanocytic Tumor: An Unusual and Distinctive Entity of Uncertain Biological Potential

We report a case of a squamomelanocytic tumor of the skin. Clinically, the lesion was felt to be a melanocytic or vascular tumor but histologically was characterized by epithelioid cells with focal squamous differentiation. Immunohistochemical staining showed that half of cells stained with MNF116 and a smaller proportion stained with S100 and Melan A. A third population did not stain with either set of antigens. The lesion has some similarities to a melanocytic matricoma but no evidence of matrical differentiation. The biological potential of this distinctive tumor is not known because so few have been reported.

An Unusual Composite Pilomatrix Carcinoma With Intralesional Melanocytes: Differential Diagnosis, Immunohistochemical Evaluation, and Review of the Literature

We report a case of an extremely rare histologic combination of pilomatrix or pilomatrical carcinoma with admixed melanocytes within the same tumor mass. Pilomatrix carcinoma is a neoplasm of low-grade malignancy that is characterized by a tendency for recurrence but low risk of metastasis. A 77-year-old male presented with a nodule on the bridge of the nose that was excised. Histologically, it was typified by asymmetry and poor circumscription, the presence of several variably sized and shaped basaloid aggregations, and surface ulceration. The tumors were composed of pleomorphic basaloid cells with prominent nucleoli and frequent mitoses (some of which were atypical) accompanied by central areas with keratotic material, shadow cells, and foci of necrosis. In addition, intermingled with the pilomatrix carcinoma, several easily identified pigmented cells with dendritic processes were present singly and as small aggregates. There was no atypia associated with the melanocytic component. Immunohistochemistry revealed the CK14 to be positive mainly within the keratinizing and the squamous epithelial elements of the tumor. The melanocytic component was strongly immunoreactive for S100, melanoma cocktail (HMB45 and Melan-A), and microphthalmia transcription factor. Pilomatrix carcinoma with melanocytes should be distinguished from the conventional pilomatrixoma with pigmentation, melanocytic matricoma, melanoma, and pigmented basal cell carcinoma with matrical differentiation. Clinicians and pathologists should be aware of the occurrence of pilomatrix carcinoma with melanocytes because of its potential for diagnosis as melanoma. This peculiar lesion recapitulates the intimate relationship existing between matrical epithelium and melanocytes in the embryonal hair follicle or in the anagen stage of the hair cycle. It is possible that sun damage played a role in stimulating migration of melanocytes among matrical cells in this case.

Cell adhesion protein expression in melanocytic matricoma

Melanocytic matricoma is a rare neoplasm thought to recapitulate the hair follicle in anagen. The tumor forms a nodule in the dermis containing basaloid, intermediate and shadow cells admixed with pigmented melanocytes dispersed as single dendritic cells. Because cadherins and catenins are crucial in the development of hair tumors, we examined the expression of E(epithelial)-, P(placental)-, N(nerve)-cadherin and beta-catenin in a melanocytic matricoma. A 66-year-old Caucasian woman with a history of breast cancer presented with a pigmented nodule on the shoulder. Pathology revealed a melanocytic matricoma with S-100 and HMB45-positive melanocytes. E- and P-cadherin were localized at the cell membrane of basaloid and differentiating keratinocytes, and in melanocytes, recapitulating the anagen hair. Both cadherins were absent in shadow cells. N-cadherin was not expressed. Beta-catenin had a differential distribution, in the nucleus and cytoplasm of basaloid cells, but at the cell membrane in differentiating cells and negative in shadow cells, paralleling the expression of E- and P-cadherin. Our results support the previously hypothesized resemblance of the tumor to the hair bulb in anagen and suggest a transcriptional role of beta-catenin in the development of this rare neoplasm.

Melanocytic Matricoma: A Distinctive Clinicopathological Entity

Melanocytic matricoma is a rare recently reported entity. It usually presents as pigmented, dark-papular, crusted lesion on sun-damaged skin of adult patients. Histopathologically, these lesions consist of well-circumscribed nodules with groups of “shadow cells” or “ghost cells” (matrical/supramatrical cells) and prominent pigmented dendritic melanocytes. It differs from matricomas and pilomatricomas by its lack of calcification, cyst formation, granulomas, and connections to the epidermis and other adnexal structures. The clinical differential diagnosis includes hemangioma, pigmented basal cell carcinoma, and melanoma. Melanocytic matricoma presumably is the representation of an epithelial-melanocytic interaction in the anagen phase of the hair cycle, and the melanization is due to normal melanocytes colonizing a neoplastic proliferation. A extensive search of the medical literature revealed 5 reports of benign melanocytic matricomas and 2 malignant counterparts. We present 2 additional cases of melanocytic matricoma with clinicopathologic correlation. The first case is from the dorsum of the hand of a 70-year-old white male and the second from the preauricular area of an 82-year-old white male, both with prior history of skin cancer. The small size, well-circumscribed appearance, and the symptom-free nature signifies benignity. However, if cytologic atypia is present, it is indicative of malignant behavior. Correct interpretation of melanocytic matricoma is extremely important due to its clinical and histopathologic overlap with other more ominous lesions.

Melanocytic Matricoma in a Dog

We report a tumor that developed at the root of the tail in a male, 2-year-old Shih Tzu dog. Histologically, the tumor consisted of basaloid epithelial cells, with shadow cells and neoplastic melanocyte proliferation. Immunohistochemically, epithelial components were positive for keratin/cytokeratin but basaloid cells were negative. Mononuclear or multinuclear melanocytes were positive for vimentin, S-100 protein, and HMB-45. In conclusion, this dog was diagnosed with canine melanocytic matricoma on the basis of the similarity of the histologic and immunohistochemical features in humans, and it may be the first case in an animal.

Pathologic quiz case: a 69-year-old man with a brown-black facial papule. Melanocytic matricoma.

Pathologic quiz case: a 69-year-old man with a brown-black facial papule. Melanocytic matricoma.

Is Melanocytic Matricoma a Bona Fide Entity or is it Just One Type of Matricoma?: Splitting Hairs...in Hair Matrix Tumors! Author's Reply

To the Editor: The authors thank Dr. K.S. Resnik for his interest in our article (1), and express our gratitude for the opportunity he offers us to rectify an erroneous reference to Ackerman's Neoplasms With Follicular Differentiation (2) (an unfortunate suggestion of one of the reviewers, in which we put excessive trust—although this is no justification!), and to apologize to Bernie Ackerman for not having credited him for the observation of the possible presence of melanocytes in neoplasms with matrical and supramatrical differentiation. As regards the objection raised by Dr. Resnik concerning the separation between matrical tumors and the so-called melanocytic matricoma, our paper referred to Carlson et al.'s report (3), which described two cases of a unique neoplasm composed of matrical cells and melanocytes recapitulating epithelial-melanocytic interaction in the follicular anagen bulb, proposing for them the name of melanocytic matricoma. In their article, Carlson et al. give in detail the reasons for considering melanocytic matricoma as a new clinicopathologic entity, and not as simply a pigmented variant of matricoma. Indeed, the presence of melanocytic proliferation is not the only feature that characterizes melanocytic matricoma; differentiation from other matrical tumors is also possible based on its solid, nodular growth pattern formed by nests of matrical cells with single or small clusters of shadow cells, the lack of cyst formation, the absence of a connection with the epidermis or adnexal epithelium, the absence of a granulomatous component or of calcifications. Furthermore, we also suggested an etiopathogenetic peculiarity of melanocytic matricoma, that is, the possible role of sunlight exposure in influencing the epithelial-melanocytic interaction during the development of the lesion, which, in our opinion, confers further autonomy on this entity (1). In conclusion, we are convinced that all these differences should be taken into consideration, and that melanocytic matricoma should be regarded as either a distinct and unique entity (especially if, as we supposed, a peculiar etiopathogenesis could justify this) or as a well-defined variant of matricoma; in the latter case it deserves accurate description, since, as happened in our case, the intriguing histologic appearance of the neoplasm did not allow us to exclude a potential malignant behavior. Clara Rizzardi, M.D. Mauro Melato, M.D.