Sclerosing epithelial hamartoma

The clinical aspects and histological details of sixteen examples of an epithelial hamartoma are reported. Similar cases have previously been described as solitary trichoepithelioma. However, the histological features are distinct and warrant a separate designation. The importance of histological differential diagnosis is emphasized.     

Cutaneous lymphadenoma

Lymphoepithelial neoplasms are biphasic tumours that contain both epithelial and lymphoid components. This heterogeneous group includes benign cutaneous lymphadenoma (CL), malignant lymphoepithelioma-like carcinoma of the skin and dermal thymus. We present two cases of CL in male subjects of 14 and 64 years of age. The latter man had a history of multiple basal cell carcinomas (BCCs) and solar keratoses. Histological sections of both tumours revealed similar features of an invasive non-ulcerated tumour with a mixed architecture of BCC and trichoepithelioma. Immunocytochemical examination revealed a biphasic epithelial tumour of follicular differentiation, possibly a variant of trichoepithelioma or a BCC. Within the epithelial islands there was a heavy infiltration that was confirmed as CD3-positive T cells and S-100-positive dendritic cells by immunocytochemistry.     

CD-34 and Ki-67 staining patterns of basaloid follicular hamartoma are different from those in fibroepithelioma of Pinkus and other variants of basal cell carcinoma

BACKGROUND AND AIMS: Basaloid follicular hamartoma is a rare disorder regarded as a developmental malformation. It may be solitary or generalized, linear or regionalized, and is sometimes associated with myasthenia gravis or alopecia. We compared immunohistochemical staining patterns of selected markers in order to differentiate this hamartoma from fibroepithelioma of Pinkus, a basal cell carcinoma variant it can be confused with. METHODS: The expression of three immunohistochemical markers--CD-34, Ki-67, bcl-2--was studied in a basaloid follicular hamartoma and in a fibroepithelioma of Pinkus. Two basal cell carcinomas, a nodular and a fibrosing type, and a trichoepithelioma were included as controls. RESULTS: Basaloid follicular hamartoma shows a low proliferation index and an at least focally circumferential expression of CD-34 around the epithelial strands. This compares to the findings in trichoepithelioma. In contrast, fibroepithelial tumor of Pinkus and two other basal cell carcinoma subtypes display a high proliferative index and an absence of CD-34 expression around the epithelium. These findings support the non-neoplastic nature of basaloid follicular hamartoma.     

Trichoepithelioma associated with cellular blue nevus

BACKGROUND: Epithelial elements, such as trichoepithelioma, are occasionally associated with melanocytic nevi. OBJECTIVE: A case of trichoepithelioma in association with cellular blue nevus is reported. METHODS AND RESULTS: A solitary, pigmented nodule was removed from the scalp of a middle-aged woman. Histopathologic examination demonstrated a circumscribed cellular blue nevus within which were embedded epithelial strands and cystic structures consistent with trichoepithelioma. CONCLUSION: Trichoepitheliomas have been described in relation to common acquired nevi, but an association with a blue nevus is rare. The intimate admixture of trichoepithelioma within the nodule of a nevus supports the concept of epithelial induction by melanocytic nevi.     

Malignant transformation of multiple familial trichoepithelioma: case report and literature review

Patients with the autosomal-dominant form of multiple familial trichoepithelioma develop numerous tumours on the face, neck and upper trunk, beginning in childhood. Malignant transformation of such lesions is quite rare; only one case of "malignant trichoepithelioma" has been reported previously, inferring pilomatrix carcinoma on a histological observation. We report here the case of a patient who developed a malignant neoplasm in a long-standing trichoepithelioma lesion on her buttock. Histopathology revealed a transformation zone between the trichoepithelioma and a malignant tumour mass. This case also showed several features of a malignant neoplasm of trichoblastic origin.     

A poroid neoplasia arising close to a seborrheic keratosis and a trichoepithelioma.

A 69-year-old woman had a well-defined, slightly raised, brownish, keratotic plaque with an eccentric group of roughly circular, bluish, dome nodules on her right scapular area. Histological study revealed the presence of an eccrine poroma demonstrating features of eccrine poroma, hidroacanthoma simplex, and dermal duct tumor and arising in a lesion of seborrheic keratosis and a trichoepithelioma. In the eccrine poroma region, an area with malignant changes was evident. The findings in this case support the view of eccrine poroma as a spectrum of histological variants and the possibility of malignant transformation from a eccrine poroma towards porocarcinoma. The association with seborrheic keratosis is most probably coincidental, and the trichoepithelioma was probably due to induction of the tumoral stroma on adjacent follicular epithelia.     

Pigmented dermatofibrosarcoma protuberans with prominent meningothelial-like whorls

Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive skin tumor. In addition to the conventional type, several morphologic variants have been described. Recognition of these uncommon variants will facilitate the diagnosis. We report herein a peculiar case of pigmented DFSP (Bednar tumor) with prominent meningothelial-like whorls, a distinctive pattern that has not been described previously in DFSP. The tumor occurred in a 40-year-old man who presented with a slowly growing mass on his left shoulder. The overall histological features were consistent with Bednar tumor. However, unexpected numerous meningothelial-like whorls were found in some areas of the tumor. Like the tumor cells in typical areas of Bednar tumor these meningothelial-like whorls were also positive for CD34 but negative for epithelial membrane antigen and S100 protein. The meningothelial-like whorls in Bednar tumor represent an eccentric arrangement of the tumor cells. We propose the term 'pigmented DFSP with prominent meningothelial-like whorls' to highlight the distinctive pattern of this novel DFSP variant.     

"Proximal-type" epithelioid sarcoma in a young girl

Epithelioid sarcoma is a rare, malignant soft-tissue neoplasm occurring on the distal extremities of young adults. Its histologic features consist of a proliferation of rounded to plump, spindle-shaped cells with abundant eosinophilic cytoplasm around areas of necrosis, simulating a granulomatous process. Recently a different type of epithelioid sarcoma has been described and named "proximal-type" epithelioid sarcoma. It is found mostly in the pelvic and perineal areas of young to middle-aged adults. On microscopic examination, the tumor is characterized by a proliferation of epithelioid-like cells with rhabdoid features in the absence of a granuloma-like pattern, and immunohistochemically it coexpresses vimentin, cytokeratin, epithelial membrane antigen, and CD34. As we found no report of proximal epithelioid sarcoma in the dermatologic literature, we describe an additional case in a 12-year-old girl. This type of tumor appears to be somewhat more aggressive than the classical, distal type and it should be considered in the differential diagnosis of tumors showing rhabdoid features, in particular extrarenal malignant rhabdoid tumor.     

Reactive and malignant "angioendotheliomatosis": a discriminant clinicopathological study

In order to determine whether or not phenotypic differences existed between reactive angioendotheliomatosis (RAE) and malignant angioendotheliomatosis (MAE), we studied the histological and immunohistochemical features of 4 and 8 cases of these lesions, respectively. Antibodies to leukocyte common antigen (LCA), specialized B- and T-lymphocytic determinants, Factor VIII-related antigen (FVIIIRAG), blood group isoantigens A, B, and H (BGI), epithelial antigens, vimentin, and actin; and Ulex europaeus I lectin (UEL) were utilized. Cutaneous lesions in all cases of MAE were part of a disseminated, fatal, intravascular cellular proliferation, with highly atypical cytological features. Because one of the patients in this group had cardiac valvular vegetations at autopsy, this case had been reported previously as representative of RAE. However, the latter example, as well as all others of MAE, stained strongly for LCA, B-cell antigens, and vimentin in tumor cells. FVIIIRAG was seen focally in 6 cases, in cells entrapped in platelet-fibrin thrombi; however, UEL binding and reactivity for BGI were uniformly absent. Conversely, RAE was typified by a cytologically-bland intravascular proliferation, with actin-positive, perivascular, pericytic cuffs. All 4 patients in this group had cutaneous involvement only, and the lesions tended to be self-resolving. One had pulmonary tuberculosis, but evidence for an underlying infection was absent in the remainder of RAE cases. Immunohistologically, RAE displayed universal reactivity for FVIII-RAG, BGI, UEL, and vimentin, and negativity for LCA in intravascular cells. Neither MAE nor RAE showed the presence of epithelial determinants. These data indicate that MAE and RAE are clinicopathologically distinct entities, showing lymphoid and endothelial features, respectively. Because of the phenotypic properties of the former condition, it would appear advisable to substitute the term "intravascular lymphomatosis" for "malignant angioendotheliomatosis".     

Malignant hair matrix tumor ("malignant trichoepithelioma") arising in the setting of multiple hereditary trichoepithelioma

An unusual adnexal tumor on the scalp of a 59-year-old woman with hereditary trichoepithelioma is reported. After the initial removal, the tumor recurred twice during a 4-year period. Mohs micrographic surgery resulted in full excision of the lesion. Two years later there was no evidence of recurrence. Histologic examination of the tumor showed it to merge with adjacent areas of classic trichoepithelioma. The tumor showed cytologic atypia, mitotic figures, necrosis, deep infiltration, and features of pilar differentiation including clear cells, reminiscent of cells of the follicular outer root sheath, and focal shadow-cell formation. The differential diagnosis of this malignant follicular neoplasm included pilomatrix carcinoma and basal-cell carcinoma with matrical differentiation. The unique clinicopathologic features, however, raised consideration of a "malignant trichoepithelioma."     

Two cases of desmoplastic trichoepithelioma

Desmoplastic trichoepithelioma is a rare tumor that usually exhibits the distinct clinical features of a solitary granuloma annulare-like growth on the face. We experienced two cases of desmoplastic trichoepithelioma, one of which showed unusual clinical features and the other of which was a typical case. The first case was a 20-year-old female who presented with a five year history of a solitary yellowish nodule, 5 mm in diameter, centrally between the eyebrows. There was no central dimple or elevated border. The other case was a 40-year-old female who presented with a ten year history of a solitary nodule, 6 mm in diameter on her left cheek. The latter lesion had a typical depressed area in the center of the nodule with elevated borders and could be clinically diagnosed as desmoplastic trichoepithelioma. The histopathological examination revealed that both of them were desmoplastic trichoepithelioma. Histopathological comparison of the two specimens suggested that the clinical dimple in the center of the first tumor might be the result of stromal dystrophic changes induced by the tumor.     

Familial trichoepithelioma of unusual distribution

Two cases are reported of multiple trichoepithelioma of unusual distribution in two girls who are close relatives. The clinical and histological features of this condition are discussed.     

Cutaneous lymphadenoma: report of 2 cases.

Cutaneous lymphadenoma is a recently described tumor with a distinctive histological picture associating a basaloid epithelial proliferation and intraepithelial lymphocytes; it seems to represent a benign adnexal neoplasm of uncertain histogenesis. We documented 2 additional examples of cutaneous lymphadenoma with typical histological features; the contiguity of some tumor lobules with preexisting follicular structures was noted. In 1 case, a cutaneous osteoma was present below the tumor. On immunostainings, S-100 protein revealed numerous dendritic intraepithelial and stromal cells. The basaloid proliferation was positive for broad-spectrum keratin antibodies, but negative for KL1 antibody. In addition, several areas were positive for involucrin within tumor lobules. Our findings are consistent with a pilosebaceous origin of cutaneous lymphadenoma.     

Desmoplastic trichoepithelioma. Clinical aspects, histology and differential diagnosis

Twelve desmoplastic trichoepitheliomas (DT) including one recurrent tumor from 9 patients are described by their clinical and histopathological features with special reference to the differential diagnostic aspects. DT typically appear as dimple lesions with raised edges in the faces of young females and histologically is composed of epithelial sheets and keratinized or calcified cysts in a desmoplastic stroma. A case showing cellular pleomorphism and followed by a relapse may represent an aggressive variant of DT. DT must be distinguished from syringoma, trichoepithelioma and especially basal cell carcinoma (BCC).     

Trichogerminoma: a rare cutaneous adnexal tumor with differentiation toward the hair germ epithelium

In 1992, Sau and colleagues described 14 cases of a rare cutaneous adnexal tumor with differentiation toward the hair germ epithelium. All cases in their study displayed a unique constellation of histological features which allowed the authors to consider the neoplasm to be a distinct entity and to designate it as 'trichogerminoma' (TG). We present a case of an adnexal tumor identical to that described as TG and report the immunophenotypical features of this neoplasm for the first time. A biopsy from a 41-year-old man revealed a well-demarcated epithelial tumor composed of multiple lobules located in the deep dermis without connection to the overlying epidermis and surrounded by a fibrous pseudocapsule. The tumorous lobules were composed of uniform basophilic cells with vesicular nuclei, dispersed chromatin and prominent nucleoli showing no prominent peripheral palisading. Some of the lobules had the appearance of densely packed 'cell balls' with peripheral condensation of the tumor cells. The stroma showed a moderate number of fibroblasts and mast cells. Reticulum staining revealed fine reticulum fibers surrounding the tumor aggregates with accentuation of the 'cell balls'. Immunohistochemically, the tumor cells expressed AE1/AE3, CK5/8, CK5/6, CAM5.2 and stained negatively for CK20, CK7, calretinin, Lu-5 and Thomsen- Friedensreich antigen. There was no increase in the numbers of CK20-positive Merkel cells in the epidermis overlying the tumor; however, a few Merkel cells were scattered in some tumor lobules. In addition, we stained 6 trichoblastomas (TBs) and found a particular pattern of calretinin expression in this tumor which was not observed in our case of TG. We conclude that pathological features allow the delineation of TG as a distinct adnexal neoplasm. Histological differential diagnosis includes basal-cell carcinoma (pilar type), large nodular TB, trichoblastic fibroma, trichoepithelioma, tricholemmoma, pilomatricoma and matrical carcinoma.     

Giant solitary trichoepitheliomas located in the perianal area: a report of three cases

Very large solitary trichoepitheliomas which arose in the perianal region in three patients are described. Although these tumours showed a striking histological similarity to classical multiple or solitary trichoepitheliomas of the face, they differed in their massive size, unusual location and by their involvement of deeper tissue. We suggest that giant solitary trichoepitheliomas is a distinct variant of trichoepithelioma that may have a predilection for the perianal region. At this site this rare tumour must be distinguished from basal cell carcinoma of the perineum and from malignant basaloid (cloacogenic) carcinoma of the anal canal.     

Scleromyxedema with an interstitial granulomatous‐like pattern: a rare histologic variant mimicking granuloma annulare

Scleromyxedema is the generalized and sclerodermoid form of lichen myxedematosus. Its typical histological features include a diffuse deposition of mucin in the papillary and mid reticular dermis, an increased of collagen deposition, and a proliferation of irregularly arranged fibroblasts. We describe a 76‐year‐old man presenting with scleromyxedema associated with IgGλ monoclonal gammopathy whose biopsy showed histological features of an interstitial granulomatous‐like process consistent with interstitial granuloma annulare. The significance of these unusual granulomatous findings in the setting of scleromyxedema are unknown and have been described only once in the literature. This observation expands the spectrum of scleromyxedema and highlights the difficulty in diagnosing this disabling condition. Rongioletti F, Cozzani E, Parodi A. Scleromyxedema with an interstitial granulomatous‐like pattern: a rare histologic variant mimicking granuloma annulare.     

Desmoplastic trichoepithelioma nosology. Reappraisal about a case developed on a varicella scar

We report the case of a 51-year-old woman who presented with a progressive elevation of the border of an old varicella scar. The lesion which was clinically diagnosed as a basal cell carcinoma turned out to be a typical desmoplastic trichoepithelioma. The development of desmoplastic trichoepithelioma in an area of scarring has not been previously reported. The nosology of this tumor is discussed with particular emphasis on its possible relationship to morphoeic basal cell carcinoma, thus questioning it as a true tumor sui generis.