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Pilomatrical Carcinoma (PC) is a rare malignant adnexal tumor with matrical differentiation. Its benign counterpart (Pilomatrixoma) is diagnosed much more frequently in daily pathological practice. Both entities share genetic alterations but the malignant counterpart acquires mutations that make it develop an aggressive behavior [1]. We describe a 33-year-old man who presented with a 7 x 6 cm nodular ulcerated lesion in the left ear with markedly accelerated growth in the last month. Incisional biopsy was referred to us with suspicion of squamous cell carcinoma versus pyogenic granuloma. Histologic sections showed ulcerated fragments infiltrated by a basaloid cell proliferation interspersed with groups of “ghost cells”. The neoplastic cells were arranged in irregular sheets with infiltrative borders. Groups of Squamous cells with trichilemmal keratinization and foci of necrosis were also identified. The biopsy was diagnosed as an adnexal neoplasm with pilomatrical differentiation, suggesting its complete resection with safety margins due to the presence of aggressive characteristics. The subsequent study of the excisional biopsy showed similar characteristics to those previously described. Notoriously, focal infiltration of the auricular cartilage was identified, leading us to the undoubted diagnosis of pilomatrical carcinoma.

Pilomatrical carcinosarcomas are very rare tumors. To the best of our knowledge, only nine cases diagnosed with pilomatrical carcinosarcomas have been reported. The present study reported on a case of pilomatrical carcinosarcoma in the posterior part of the left auricle of a 100-year-old male patient. The tumor histologically comprised the following two components: Pilomatrical carcinoma and undifferentiated spindle cell sarcoma. The pilomatrical carcinoma comprised atypical basaloid cells and shadow cells. The basaloid cells had basophilic cytoplasm, clear nucleoli and deeply stained nuclear chromatin. The undifferentiated spindle cell sarcoma comprised atypical spindle cells. Both components contained numerous mitotic cells. The boundary area between the carcinoma and sarcoma smoothly transitioned into each other. The carcinoma cells and a portion of the sarcoma cells were positive for β-catenin in the cytoplasm with or without the nuclei. These results suggested that the two components developed from the same origin.

The diagnosis of pilomatricoma, the most common matrical tumor, is generally straightforward; however, it exhibits diverse histology associated with various morphological stages and several clinical variants, and matrical differentiation can occur in various neoplastic diseases. A 56-year-old man was admitted to our hospital to resect an 11.0-cm skin tumor on his right shoulder. Because of its large size and surface irregularities, including multiple erosions and ulcers, cutaneous malignancies were clinically suspected. Histologically, the tumor formed numerous nodules with marked matrical differentiation in the superficial to deep dermis. Although the tumor was macroscopically asymmetrical and irregular, each nodule was microscopically round-shaped and consisted of basaloid cells without marked atypia, atypical mitoses, or lymphovascular invasion. Immunohistochemically, the tumor cells were positive for beta-catenin, LEF-1, and PHLDA-1, consistent with their pilomatrical differentiation. We diagnosed the case as a giant pilomatrical tumor with uncertain malignant potential, considering its "contradictory" features, namely, the worrisome histoarchitecture, such as the asymmetrical silhouette, but bland-looking cytological appearance. Unlike typical pilomatrical tumors, this tumor contained numerous epidermal components with features similar to those of the dermal components, resulting in a unique macroscopic and histological appearance. Our case broadens the known histological diversity of pilomatrical tumors.

We report a case of pilomatrical tumor showing intermediate histological features between pilomatricoma and pilomatrical carcinoma. The lesion recurred twice with the same histological features. Similar cases were was probably called aggressive or proliferating pilomatixoma; we think that the term pilomatrical tumor of low malignant potential is more suitable for this lesions. Excision with wide free margins and follow-up are recommended.

Pilomatrical carcinoma is one of the rare adnexal tumors with only 140 reported cases according to recent literature. The tumor has a propensity to arise in posterior neck, upper back and lower extremities and has 100% mortality if metastasizes. Hence, it is imperative to document the illusive nature of this deceptive tumor. The case under discussion is that of a 70-year-old male presenting with multiple small to large non-tender firm lesions over the scalp. The tumor, labeled as proliferative trichilemmal cyst, radiologically was excised, and the scalp was reconstructed by mobilization of the local area. Extensive sampling of the specimen received revealed morphology of pilomatricoma and trichilemmal cysts with a focus of stromal invasion in one of the lobules of pilomatricoma. Hence, a diagnosis of pilomatrical carcinoma was made, and the patient is on close follow-up since 1 year post-operatively with no signs of recurrence or cervical lymphadenopathy. Though of low malignant potential, the tumor is said to have recurrence potential. The prognosis is variable depending on the evidence of metastasis found if, at all, the mortality is 100%. Hence, extensive sampling and accurate diagnosis are essential to rule out the possibility of malignancy.

Matrical carcinoma with melanocytic hyperplasia (MCMH), previously referred to as malignant melanocytic matricoma, is a rare variant of the uncommon pilomatrical carcinoma, occurring most often on the head/neck and upper backs of middle-aged men. Nodular lesions may resemble pigmented basal cell carcinoma or melanoma clinically. We present a case of MCMH in a Hispanic patient with history of melanoma. Histopathological clues to appropriate diagnosis include basaloid cells, numerous atypical mitotic figures, matrical differentiation, shadow cells, strong diffuse nuclear and cytoplasmic expression of s-catenin, and interspersed pigmented dendritic melanocytes.

Malignant pilomatricoma (pilomatrical carcinoma) is a rare, locally occurring malignant tumor with a high rate of recurrence in the case of incomplete excision. This tumor has two characteristics. First, recurrences of pilomatrical carcinoma are common; second, distant metastasis is rare, but if it occurs, it is very fatal. It has characteristic features of high mitotic counts, cellular atypia, and local invasion. Although fine needle aspiration and excisional biopsy could help to confirm this tumor diagnosis, pathologic findings are critical. Pilomatricomas have some characteristic features in histological aspect, such as epithelial islands of basaloid cells and shadow cells or ghost cell. Also, various types of immunohistochemical staining are used to confirm the diagnosis. Despite the lack of clear surgical criteria, treatment is a wide local excision with histologically clear resection margins with or without adjuvant radiotherapy.

We present a case report of the exceptionally rare pilomatrical carcinosarcoma in an even rarer pediatric age group, a 9-year-old female patient. The tumor showed biphasic pilomatrical carcinoma and malignant sarcomatous transformation. To date, the patient is healing well without signs of recurrence. Although limited clinical follow-up is available due to the recent diagnosis, this case may provide a rare look at the clinical outcome of this very rare tumor.

Pilomatrical carcinoma is a rare tumor originating from skin appendages, usually occurring between the 5th and 7th decade of life. We present a case of an exceptionally young, 21-year-old patient with surprisingly rapid tumor progression and answer the question, what was the reason for such uncontrolled tumor growth. The main concern is the diagnostic challenge and a peculiar, one week race against time and tumor progression so that the least disfiguring surgery could be done.

Osteoma cutis, the development of bone in the dermis and/or subcutaneous fat, can occur as either a primary or secondary condition. Perforating osteoma cutis is rare. A man with a solitary lesion of perforating osteoma cutis is described and the features of individuals with a single perforating osteoma cutis skin lesion are reviewed. A solitary lesion of either primary or secondary perforating osteoma cutis has only been observed in two men and one woman; the lesions had been present from less than one month to 19 or 20 years prior to establishing the diagnosis. The lesion was either located on the forehead (two men) or the breast (one woman). The erythematous (two lesions) or flesh-colored nodules ranged in size from 8×8 millimeters to 1.5×0.5 centimeters. Each had epidermal perforation by bone through a central area that was either crateriform or crusted or keratotic. The clinical differential diagnosis included keratoacanthoma, phlebolith, pilomatricoma, pilomatrical carcinoma, and squamous cell carcinoma. The perforating osteoma cutis lesion was successfully treated with either excision or shave biopsy without recurrence at either 10 or 12-months follow-up.

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.

Basal cell carcinoma with matrical differentiation is an extremely rare variant. To date, only 12 cases have been described in the literature. This tumor is a typical basal cell carcinoma with basaloid nests containing shadow cells identical to those of pilomatricoma and pilomatrical carcinoma. We present two additional cases and have investigated the immunoprofile of .-catenin and osteopontin with the aim of determining both their biological significance and possible diagnostic utility. The morphological and immunohistochemical features of these cases that we have found suggest that basal cell carcinomas with matrical differentiation belong to a spectrum of lesions deriving from hair follicles in which .-catenin plays an important role in the tumor development, differentiation, and behavior.

A 58-year-old man developed an extensive pilomatrical carcinoma in the left axilla. Clinically, a squamous cell carcinoma was suspected. Histological examination revealed the presence of proliferating basaloid cells with many atypical mitoses and mass necrosis infiltrating into the subcutaneous tissue. The tumor was removed by micrographic surgery with a 2 cm safety margin. Histological examination of 2 regional lymph nodes as well as further diagnostic procedures ruled out metastases. We review the clinical and histopathological differences between pilomatricoma and pilomatrical carcinoma, as well as the published cases of the malignant variant.

We report on 9 patients with pilomatricomas that showed unusual histopathologic features. Our patients were mainly elderly individuals (age range 42 to 88 years; mean age 70.1 years) who presented solitary cutaneous nodules situated on the head and neck (7 neoplasms), upper arm (1 neoplasm), and back (1 neoplasm). All the lesions were treated by simple excision. Follow-up data available in 7 of the 9 patients (mean follow-up, 17 months) revealed local recurrences in 1 patient whose lesion recurred 3 times. No lymph node involvement or distant metastases were recorded in any of our cases. Histopathologically, most neoplasms were characterized by a relatively large lesion in the dermis that in some cases showed extension to the subcutis. Each lesion was predominantly composed of a lobular proliferation of basaloid cells in association with adjacent focal areas containing eosinophilic, cornified material with shadow cells. In some cases, relatively large areas of shadow cells were present, whereas, in others only small foci of shadows cells were observed. Cytomorphologically, the basaloid cells showed features of matrical and supramatrical cells of a normal hair follicle and exhibited variable nuclear atypia and mitotic figures. The overall architectural pattern of the neoplasms was different from that of large fully developed stereotypical pilomatricomas that maintain a cystic character with basaloid cells predominantly aligned at the periphery. Based on the histopathologic findings, namely the presence of a large, lobular proliferation of basaloid cells in association with small to large foci of shadow cells, we interpreted these neoplasms to be a distinctive proliferative variant of pilomatricoma and propose the designation "proliferating pilomatricoma." Proliferating pilomatricomas should be differentiated from the recently described matricoma, basal-cell carcinoma with matrical differentiation, and matrical carcinoma (pilomatrical carcinoma).

A 36-year-old Japanese female with pilomatrical carcinoma is described. she noted a bean-sized asymptomatic subcutaneous nodule on her right upper arm about three years before visiting our hospital. She left the nodule as it was. But, about 2 years and a half later, the nodule rapidly enlarged and elevated. Soon later, the nodule was eroded and ulcerated. Biopsy performed at a hospital suggested malignant tumor, and she was refferd to us.At the first visit to us, an ulcerated elastic hard nodule, 77×71×21mm in size, was seen on her right upper arm.Histopathologic examination revealed that the lesion had reached the deep layer of the subcutaneous tissue. The nodule was composed of sheets and nests of basaloid cells with cystic spaces containing shadow cells. The sheets and nests were various in size and shape. The basaloid cells predominated over the shadow cells. The basaloid cells were compactly arranged. Atypical nuclei, many mitotic figures and some necrotic foci was detected in the nests of the basaloid cells. Infiltrative proliferation into the surrounding desmoplastic stroma was observed.She underwent the wide resection of the nodule. There has been no evidence of recurrence for 1 year after surgery.

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.

Shadow cells are characteristic of pilomatricoma, although they have been described in other cutaneous and visceral neoplasms, particularly endometrioid adenocarcinomas of the female genital tract. We describe a metastasis of an ovarian endometrioid adenocarcinoma with shadow cells to the skin that was initially misinterpreted as a pilomatricoma. We compare the histology of the ovarian neoplasm to 21 pilomatricomas. This is the first reported case of a cutaneous metastasis of a visceral neoplasm mimicking a primary pilomatrical neoplasm.

Pilomatricomas are the most common superficial pediatric tumor and current literature demonstrates that they can be diagnosed clinically. Excisional biopsy is recommended for diagnosis and curative treatment. Because the recurrence rate after excision is low, pilomatrical carcinoma should be considered in the case of local recurrence. Multiple pilomatricomas, on the other hand, are rare. They have been associated with various syndromes, of which myotonic dystrophy has been the most described. We present a patient with multiple pilomatricomas in an otherwise well 13-year-old girl and our management of her in relation to current literature.

Pilomatrixoma, a neoplasm of hair germ matrix origin, is one of the most common cutaneous appendage tumors in patients 20 years of age or younger. Our review of cutaneous adnexal tumors in the first 2 decades of life showed that pilomatric lesions accounted for approximately 75% of cases. We examined 76 tumors from 69 patients between the ages of 8 months and 19 years (average age, 8 years). The female-to-male ratio was 3:1. We noted a predilection for the head and neck region, as has also been reported by other investigators. Sixty-nine tumors were examples of typical or classic pilomatrixoma; four of them showed the unusual histologic feature of transepidermal elimination or perforation. None of the tumors in the typical category recurred during a follow-up period that averaged 8.7 years. Seven of the lesions with atypical histologic features were examples of aggressive pilomatrixoma (three cases) and pilomatrical carcinoma (four cases). The average age of these seven patients was similar to that of the overall group. The pilomatrical carcinomas were characterized by invasive nests of tumor cells with irregular borders, large vesicular nuclei, prominent nucleoli, multiple mitotic figures, and focal necrosis. A desmoplastic stroma surrounded the infiltrating nests of tumor. Two of the four pilomatrical carcinomas recurred 2 and 6 months, respectively, after initial excision. The aggressive pilomatrixomas had a similar infiltrative growth pattern, but they did not exhibit the same degree of worrisome cytologic features. Single cell necrosis, identifiable mitotic figures, and prominent nucleoli differentiated the atypical from the typical pilomatrixomas. One of the three aggressive pilomatrixomas recurred after 2 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Previous studies suggested that mutant beta-catenin gene cells in cutaneous adnexal tumors with matrical differentiation contribute to their tumorigenesis. Except for pilomatricoma and pilomatrical carcinoma, only a handful of other cutaneous adnexal tumor types have been studied. DNA was extracted from 86 lesions including 17 proliferating tricholemmal and trichilemmal tumors, 15 trichoblastomas, 7 trichoadenomas, 4 pilomatricomas, 1 pilomatrical carcinoma, 4 basal cell carcinomas (BCCs) with shadow cells, 2 trichofolliculomas, 3 BCCs with sebaceous differentiation, 9 sebaceous adenomas, 6 sebaceomas, 14 sebaceous carcinomas (both ocular and extraocular forms), 2 gigantic horns, and 2 apocrine mixed tumors with shadow cells and subjected to polymerase chain reaction with newly designed primers encompassing glycogen synthase kinase-3beta phosphorylation sites of the CTNNB1 gene. Also, 3 craniopharyngiomas were studied. Sequenced polymerase chain reaction products for possible beta-catenin gene mutations showed a total of 8 alterations. These included 5 different point mutations, 3 of them identified in 2 different tumors: S23N (cribriform trichoblastoma), D32Y (pilomatricoma and craniopharyngioma), G34R (pilomatrical carcinoma and craniopharyngioma), S37F (2 BCCs with shadow cell differentiation), and G34V (craniopharyngioma). This study broadens the list of cutaneous adnexal tumors harboring CTNNB1 mutations and extends the listing of the mutations occurring in these neoplasms.

Pilomatrical carcinoma is a rare tumor without a single pathognemonic feature that distinguishes it from the benign pilomatricoma. We report a 51-year-old man with HIV, hepatitis C, and pilomatrical carcinoma.

Pilomatrix carcinoma, the malignant variant of pilomatrixoma, is a rare entity. The authors report on six patients with pilomatrix carcinoma and review the pertinent literature. The lesions showed a predilection for elderly individuals (mean age, 61 years) with a male:female ratio of 5:1, and they presented as dermal or subcutaneous tumors located on the head and neck (5 neoplasms) and chest (1 neoplasm). Tumors varied in size from 0.6 cm to 2.5 cm (mean, 1.78 cm). None of the lesions recurred after wide local excision. On scanning magnification, all tumors showed the architectural features of a malignant neoplasm (asymmetry and poor circumscription, presence of several markedly sized and variably shaped basaloid aggregations, and ulceration). The tumors were composed of pleomorphic basaloid cells with prominent nucleoli and frequent atypical mitoses accompanied by central areas with keratotic material, shadow cells, and foci of necrosis. The tumor nests were surrounded by a desmoplastic stroma and infiltrated the adjacent tissues. Vascular or perineural infiltration was not observed. In one case, the basaloid cells contained abundant melanin pigment in their cytoplasms. Pilomatrix carcinoma is a neoplasm of low-grade malignancy that should be distinguished from the conventional pilomatrixoma and its variants (aggressive pilomatrixoma and proliferating pilomatrixoma), matricoma, and basal cell carcinoma with matrical differentiation. Clinicians and pathologists should be aware of the occurrence of pilomatrix carcinoma because of its potential for distant metastases.

Background Pilomatrix carcinoma is a rare cutaneous tumor derived from follicular matrix cells with few cases documented in the literature. Objective We sought to better characterize this tumor by analyzing its epidemiologic, clinical, and histopathologic features in 13 new cases and by reviewing the literature. Methods All cases of pilomatrix carcinoma from a large regional dermatopathology practice were identified and analyzed by chart review for clinical and histopathologic characteristics. Similar characteristics were compiled from an additional 123 cases in the English-language literature. Cox proportional hazards regression models were used to determine risk factors associated with the development of metastasis for all identified metastatic tumors. Results Our 13 tumors were most common in middle-aged to older white men and presented mostly on the head/neck. Histopathologically, tumors were asymmetric, were poorly circumscribed, were composed of basaloid and "ghost" cells, had frequent atypical mitoses, and had infrequent lymphovascular invasion. Wide excision was considered the most definitive treatment modality, but local recurrence was common. When analyzing all reported cases of metastasis using statistics, metastasis was significantly associated (hazard ratio 3.45, P Limitations The retrospective, single-center design and the reliance on electronic medical records are limitations. Conclusions This study helps better characterize pilomatrix carcinoma and identifies potential predictors of metastasis.

Malignant pilomatricoma or pilomatrical carcinoma is a rare malignant hair follicle neoplasm. This tumor is locally aggressive with increased tendency to recur, but a low metastatic potential. Its histopathological diagnosis is difficult and based on a detailed evaluation of the infiltrative nature, the importance of the mummified and necrotic cell component, atypical mitoses, and perineural or vascular invasion. Surgical wide resection is the recommended treatment. It reduces the risk of focal recurrence by 50%. Here we report two new cases including one that occurred on a lesion initially diagnosed as benign pilomatricoma.