Home Translating Report News Physicians Diseases Body Sites Lab tests Search
Home Diseases and Health Information


This is a rare tumor arising within the skin and thought to be derived from adnexal structures in the skin, probably the hair follicle. It has a characteristic appearance under the microscope with a dual cell population with mixed epithelial cells and dendritic melanocytes. The importance of this disease is for the dermatopathologist to distinguish it from other more sinister entities including pigmented variants of pilomatricoma, matrical carcinoma, basal cell carcinoma and malignant melanoma.


Disease Associations  
Other Diagnostic Testing
Gross Appearance and Clinical Variants  
Histopathological Features and Variants  
Special Stains/
Electron Microscopy
Differential Diagnosis  
Commonly Used Terms  
Internet Links  


AGE Adults


Cell adhesion protein expression in melanocytic matricoma.

Department of Pathology, Duke University Medical Center, Durham, NC, USA.


J Cutan Pathol. 2007 Jun;34(6):456-60. Abstract quote

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: case confirmation of a recently described entity.

Williams CM, Bozner P, Oliveri CV, Horenstein MG.

Department of Pathology, University of South Alabama, Mobile, Alabama, USA.

J Cutan Pathol 2003 Apr;30(4):275-8 Abstract quote

BACKGROUND: In 1999, Carlson et al. reported two cases of a matrical neoplasm that recapitulates the bulb of the anagen hair follicle, which they designated as melanocytic matricoma.

METHODS: Here we report a similar case in a 78-year-old white male, who presented with a 0.4 cm purple-black firm papule in the left preauricular area.

RESULTS: Histologically, the tumor is composed of a dual cell population including admixed epithelial matrical and supramatrical cells with "shadow" cell formation and pigmented dendritic melanocytes. Immunohistochemical studies for cytokeratin highlighted the epithelial component and studies for S-100 protein, HMB-45, and vimentin confirmed the melanocytic component. The differential diagnosis considered includes pigmented variants of pilomatricoma, matrical carcinoma, basal cell carcinoma and malignant melanoma.

CONCLUSIONS: The case reported herein is the first confirmation of melanocytic matricoma, a distinctive adnexal neoplasm with characteristic clinical and pathologic features, which differentiate it from pigmented pilomatricoma.

Melanocytic matricoma: a report of two cases of a new entity.

Carlson JA, Healy K, Slominski A, Mihm MC Jr.

Division of Dermatopathology and Dermatology, Department of Pathology Albany Medical College, NY 12208, USA.


Am J Dermatopathol 1999 Aug;21(4):344-9 Abstract quote

Many reports exist of pigmented adnexal tumors containing dendritic melanocytes such as pigmented basal cell carcinomas and pigmented pilomatricomas. Correspondingly, melanocytes are a known component of the bulbs of anagen follicles. The phenomenon of melanization of adnexal tumors highlights the interrelationship between melanocytes and adnexal epithelium and may represent normal melanocytes colonizing a neoplastic proliferation.

We report on two cases of a unique tumor composed of neoplastic matrical cells with a significant component of melanocytes. Both cases presented as pigmented papules in older men (66 and 80 years, forearm and pectoral region, respectively). Histologically, these were well-defined nodular proliferations composed of variably melanized, pleomorphic, and mitotically active matrical and supramatrical cells forming clusters of "shadow cells." Admixed with the epithelial cells were numerous melanized dendritic melanocytes. Shadow cells expressed keratin 13, and a subpopulation of S-100 protein-positive dendritic cells were evident. No recurrence of any type was found after reexcisions 4 months and 2 years later.

We propose the name of melanocytic matricoma for these two heretofore unreported cases of a unique neoplasm composed of matrical cells and melanocytes recapitulating epithelial-melanocyte interaction in the follicular anagen bulb. Although their small size, circumscription and clinical course suggest a benign nature, melanocytic matricomas' cytologic atypia disclose the potential for malignant behavior.


Matrical carcinoma with prominent melanocytic hyperplasia (malignant melanocytic matricoma?) A report of two cases.

Monteagudo C, Fernandez-Figueras MT, San Juan J, Lopez D, Carda C.

Departamento de Patologia, Universidad de Valencia, Valencia, Spain.
Am J Dermatopathol. 2003 Dec;25(6):485-9. Abstract quote  

Melanocytic matricoma is a recently described lesion characterized by well-circumscribed nodules composed of matrical and supramatrical cells with clustered ghost cells, and admixed pigmented dendritic melanocytes, with no cyst formation or connection to the epidermis or pre-existing hair follicles.

Although variable cytologic atypia and frequent mitoses in the epithelial component may be present, given the well-defined margins and absence of tumor recurrences, these lesions were initially considered benign neoplasms, and not matrical carcinoma. Theoretically, the detection of numerous melanocytes in matrical carcinoma should not be surprising, but is in fact a very unusual feature. A case with extensive melanization of epithelial elements and only rare melanocytes has been reported.

We report two cases of matrical carcinoma with prominent melanocytic hyperplasia, with emphasis on the ultrastructural and immunohistochemical features. Our cases might be considered the malignant counterpart of the so-called melanocytic matricoma.

A tumor with composite pilo-folliculosebaceous differentiation harboring a recently described new entity--melanocytic matricoma.

Rizzardi C, Brollo A, Colonna A, Brutto RL, Melato M.

Unit of Pathology, University of Trieste, Italy.

Am J Dermatopathol 2002 Dec;24(6):493-7 Abstract quote

We report on a case of a peculiar tumor of the pilosebaceous unit showing a composite histologic appearance. The case presented as a pigmented crusted lesion on the back of the nose of a 62-year-old woman with markedly sun-damaged skin.

Histologically, the superficial portion of the neoplasm was composed of buds and nests of basaloid epithelium with varying degrees of pilar and sebaceous differentiation. Adjacent to this component, lobules of squamous cells with cytoplasmic glycogenation suggesting the mature outer root sheath were seen. In the underlying dermis, there was a well-defined nodular proliferation composed of variably pigmented basaloid matrical cells forming clusters of "shadow" or "ghost cells" admixed with numerous melanized dendritic melanocytes; this last component of the neoplasm was identical to a recently described entity, melanocytic matricoma. The small size, circumscription, and absence of necrosis favored benignity, although the cytologic atypia of matrical cells did not exclude malignancy.

The case is interesting not only because it is the third reported case of a peculiar neoplasm imitating the epithelial-melanocytic interaction in the embryonal hair follicle or bulb of the anagen follicle but because the part resembling melanocytic matricoma presented as a component of a complex lesion. We believe that sunlight may have played a role in the development of this peculiar neoplasm.



Pigmented Epithelioid Melanocytoma: A Low-grade Melanocytic Tumor With Metastatic Potential Indistinguishable From Animal-type Melanoma and Epithelioid Blue Nevus.

Zembowicz A, Carney JA, Mihm MC.

Dermatopathology Unit, Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, MA; and dagger Department of Laboratory Medicine & Pathology (Emeritus Member), Mayo Clinic, Rochester, MN.
Am J Surg Pathol. 2004 Jan; 28(1): 31-40. Abstract quote  

SUMMARY: In the course of a study of borderline melanocytic tumors, we observed a distinctive group of lesions characterized by features very similar to those previously described in the literature as "animal-type melanoma" and epithelioid blue nevus of Carney complex. We have designated these lesions as pigmented epithelioid melanocytoma (PEM). Herein, we present a clinical-pathologic analysis of 41 consecutive PEM from 40 patients and compare them with 11 epithelioid blue nevi from patients with Carney complex. PEM occurred in both sexes of different ethnic backgrounds, including white, Hispanic, black, Asian, and Persian.

The median age of occurrence was 27 years (range 0.6-78 years). Tumors had wide distribution with extremities being the most common site. The tumors were formed by deep dermal (mean Breslow's thickness 3.3 mm) proliferation of heavily pigmented epithelioid and/or spindled melanocytes. Five lesions were part of combined nevus. Ulceration was present in 7 cases. Tumor necrosis was present in 1 case. Regional lymph nodes were sampled in 24 cases (59%). In 11 cases, lymph nodes contained metastases (46%). Liver metastases occurred in 1 case. None of the patients died of disease. Clinical follow-up of more than a year (mean 32 months, range up to 67 months) was available in 27 cases (67%).

We found no histologic criteria separating metastasizing and nonmetastasizing PEM. Ulceration was the only feature more common in PEM than epithelioid blue nevi of Carney complex. Otherwise, they were histologically indistinguishable. Our data show that PEM is a unique low-grade variant of melanoma with frequent lymph node metastases but indolent clinical course.

We suggest that PEM be considered as a provisional histologic entity encompassing both animal-type melanoma and epithelioid blue nevus.

Macpherson and Pincus. Clinical Diagnosis and Management by Laboratory Methods. Twentyfirst Edition. WB Saunders. 2006.
Rosai J. Ackerman's Surgical Pathology. Ninth Edition. Mosby 2004.
Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 6th Edition. McGraw-Hill. 2003.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.

Commonly Used Terms

Basic Principles of Disease
Learn the basic disease classifications of cancers, infections, and inflammation

Commonly Used Terms
This is a glossary of terms often found in a pathology report.

Diagnostic Process
Learn how a pathologist makes a diagnosis using a microscope

Surgical Pathology Report
Examine an actual biopsy report to understand what each section means

Special Stains
Understand the tools the pathologist utilizes to aid in the diagnosis

How Accurate is My Report?
Pathologists actively oversee every area of the laboratory to ensure your report is accurate

Got Path?
Recent teaching cases and lectures presented in conferences

Internet Links

Last Updated June 7, 2007

Send mail to The Doctor's Doctor with questions or comments about this web site.
Read the Medical Disclaimer.

Copyright © The Doctor's Doctor