Immunohistochemical and ultrastructural observations of desmoplastic trichoepithelioma with a special reference to a morphological comparison with normal apocrine acrosyringeum

Desmoplastic Trichoepithelioma: Histopathologic and Immunohistochemical Criteria for Differentiation of a Rare Benign Hair Follicle Tumor From Other Cutaneous Adnexal Tumors

Desmoplastic trichoepitheliomas (DTEs) are benign cutaneous neoplasms that originate from the hair follicle and exhibit a preference for the facial region. This type of neoplasm is characterized by accelerated growth, with vigorous histologic and immunohistochemical features that may be confused with other skin cancers. Thus, the objective of this study is to establish a definitive diagnosis that can be widely used. This review was systematically carried out and includes case series and studies to establish valuable data that can be used for research. The articles were sought in PubMed, MEDLINE, and Google Scholar using the keywords "desmoplastic trichoepithelioma," "morphea basal cell carcinoma," "microcystic adnexal carcinoma," "syringoma," and "cutaneous breast carcinoma." From a total of 65 journal articles, we chose 42 studies describing the clinical features, etiology, histopathology, and immunohistochemical characteristics of tumors. After quality assessment, 10 studies were selected, representing the differentiating features among the four mentioned cutaneous tumors. The differential diagnosis of DTE also includes other cutaneous and follicular tumors. At present, there is no standardized grading system for trichogenic tumors, although several symptomatic terms have been offered. More recently, immunohistochemistry and histopathological studies support the differentiation between the above-mentioned cutaneous tumors. However, additional research needs to be conducted to obtain complete information regarding the specific distinct traits of the indicated cutaneous tumors.

Folliculosebaceous neoplasms: A review of clinical and histological features

Numerous benign and occasionally malignant tumors arise from the folliculosebaceous apparatus. Confusing terminology, rarity of malignant variants and overlapping histological features can lead to diagnostic uncertainty. This review highlights the clinical and histopathological features that help to classify these entities, as well as the various syndromes associated with certain members of this large family of tumors.

Desmoplastic trichoepithelioma: A clinicopathological study of three cases and a review of the literature

Desmoplastic trichoepithelioma (DTE) is a rare benign adnexal tumor with the characteristic features of asymptomatic, solitary, annular, indurated and centrally depressed papules or plaques, most commonly occurring in younger individuals on the face. Microscopically and clinically, DTE may be difficult to distinguish from other cutaneous adnexal neoplasms, particularly syringoma, cutaneous metastatic breast cancer, morpheaform basal cell carcinoma and microcystic adnexal carcinoma. The present study reports three cases of DTE. The first case was of a 45-year-old male with an asymptomatic flesh-colored plaque below the right edge of the outer canthus that had been present for seven years. The second case was of a 23-year-old female with an asymptomatic skin lesion on the right cheek that had slowly and progressively increased in size. The third case was of a 26-year-old female who presented with a hard yellowish-white plaque, which gradually grew and formed a rectangular, 3×4-cm patch, on the tip of the left brow. This plaque was present for three years without evident cause or subjective symptoms. In all three cases, the routine systemic examinations and laboratory findings were normal. Histopathological and immunohistochemical findings from incisional biopsies of the lesions were consistent with a diagnosis of DTE. DTE treatment methods and immunohistochemical markers were analyzed by reviewing clinical pathological aspects in order to avoid a misdiagnosis and to provide the best available treatment approach for DTE.

Anatomoclinical study of 30 cases of sclerosing sweat duct carcinomas (microcystic adnexal carcinoma, syringomatous carcinoma and squamoid eccrine ductal carcinoma)

BACKGROUND

Microcystic adnexal carcinoma (MAC), syringomatous carcinoma (SC) and "Squamoid eccrine ductal carcinoma" (SEDC) are rare sclerosing adnexal tumours.

OBJECTIVE

To understand the histogenesis of these tumours and possible clinical implications.

METHODS

We conducted a retrospective study of 30 cases, 18 MAC, 5 SC and 7 SEDC reviewed and classified by a panel of dermatopathology experts, with immunohistochemical analysis of keratins, including K77, a new keratin specific of eccrine ducts, and PHLDA1 expressed in adnexal structures.

RESULTS

There was a strong female predominance, with only five cases occurring in men. Patients with MAC and SC were younger (mean age 56 and 47 years) than those with SEDC (mean age 81 years). The most common localization was the cheek in SC and SEDC and the periocular area in MAC. Two cases of SEDC were found in organ transplant patients. No recurrence or metastases were observed after complete surgery of MAC, or SC (mean follow-up 7.2 years and 4.7 years), whereas one case of SEDC recurred and another could not be fully excised. MAC and SC had similar histological features, except for cysts. In MAC, calcifications, granulomas, connection to follicles, keratin expression pattern, PHLDA1 positivity and K77 negativity indicated a follicular histogenesis, whereas in SC, K77 positivity and keratin expression pattern were consistent with a differentiation towards eccrine apparatus. SEDC was composed of strands centred by ducts and nests with squamous differentiation and displayed K77 ductal positivity in all cases, a finding consistent with an eccrine origin.

CONCLUSION

Our study demonstrated that MAC and SC have similar clinical characteristics, although histogenesis differs and show arguments for the individualization of SEDC.

Cutaneous deposits

: The cutaneous deposition disorders are a group of unrelated conditions characterized by the accumulation of either endogenous or exogenous substances within the skin. These cutaneous deposits are substances that are not normal constituents of the skin and are laid down usually in the dermis, but also in the subcutis, in a variety of different circumstances. There are 5 broad categories of cutaneous deposits. The first group includes calcium salts, bone, and cartilage. The second category includes the hyaline deposits that may be seen in the dermis in several metabolic disorders, such as amyloidosis, gout, porphyria, and lipoid proteinosis. The third category includes various pigments, heavy metals, and complex drug pigments. The fourth category, cutaneous implants, includes substances that are inserted into the skin for cosmetic purposes. The fifth category includes miscellaneous substances, such as oxalate crystals and fiberglass. In this article, the authors review the clinicopathologic characteristics of cutaneous deposition diseases, classify the different types of cutaneous deposits, and identify all the histopathologic features that may assist in diagnosing the origin of a cutaneous deposit.

Calcinosis cutis: part I. Diagnostic pathway

Calcinosis cutis is characterized by the deposition of insoluble calcium salts in the skin and subcutaneous tissue. The syndrome is separated into five subtypes: dystrophic calcification, metastatic calcification, idiopathic calcification, iatrogenic calcification, and calciphylaxis. Dystrophic calcification appears as a result of local tissue damage with normal calcium and phosphate levels in serum. Metastatic calcification is characterized by an abnormal calcium and/or phosphate metabolism, leading to the precipitation of calcium in cutaneous and subcutaneous tissue. Idiopathic calcification occurs without any underlying tissue damage or metabolic disorder. Skin calcification in iatrogenic calcinosis cutis is a side effect of therapy. Calciphylaxis presents with small vessel calcification mainly affecting blood vessels of the dermis or subcutaneous fat. Disturbances in calcium and phosphate metabolism and hyperparathyroidism can be observed.

Immunophenotyping of the human bulge region: the quest to define useful in situ markers for human epithelial hair follicle stem cells and their niche

Since the discovery of epithelial hair follicle stem cells (eHFSCs) in the bulge of human hair follicles (HFs) an important quest has started: to define useful markers. In the current study, we contribute to this by critically evaluating corresponding published immunoreactivity (IR) patterns, and by attempting to identify markers for the in situ identification of human eHFSCs and their niche. For this, human scalp skin cryosections of at least five different individuals were examined, employing standard immunohistology as well as increased sensitivity methods. Defined reference areas were compared by quantitative immunohistochemistry for the relative intensity of their specific IR. According to our experience, the most useful positive markers for human bulge cells turned out to be cytokeratin 15, cytokeratin 19 and CD200, but were not exclusive, while beta1 integrin and Lhx2 IR were not upregulated by human bulge keratinocytes. Absent IR for CD34, connexin43 and nestin on human bulge cells may be exploited as negative markers. alpha6 integrin, fibronectin, nidogen, fibrillin-1 and latent transforming growth factor (TGF)-beta-binding protein-1 were expressed throughout the connective tissue sheath of human HFs. On the other hand, tenascin-C was upregulated in the bulge and may thus constitute a component of the bulge stem cell niche of human HFs. These immunophenotyping results shed further light on the in situ expression patterns of claimed follicular 'stem cell markers' and suggest that not a single marker alone but only the use of a limited corresponding panel of positive and negative markers may offer a reasonable and pragmatic compromise for identifying human bulge stem cells in situ.

Dermoscopic and Reflectance Confocal Microscope Findings of Trichoepithelioma

BACKGROUND

Trichoepitheliomas (TE) are benign neoplasms of follicular differentiation. Solitary lesions are often confused with basal cell carcinoma (BCC). Reflectance confocal microscopy (RCM) and dermoscopy are imaging tools for in vivo, noninvasive evaluation of skin lesions. To date, there has been no description of their findings in the evaluation of TE.

OBJECTIVE

Our aim is to describe the dermoscopic and RCM findings of histopathologically confirmed TE.

METHODS

Four TE were evaluated, 2 each of the desmoplastic and nondesmoplastic variants. RCM was performed on 1 of the desmoplastic and both of the nondesmoplastic lesions.

RESULTS

Dermoscopically, all of the lesions showed arborizing telangiectasias. The desmoplastic lesions also had an ivory-white background throughout. RCM showed oval, darker-appearing tumor islands that contained brightly refractile material, consistent with keratin horn cysts at the center, as well as parallel bundles of highly refractile dermal collagen surrounding the tumor islands.

CONCLUSION

The ivory-white background throughout the lesion seen on dermoscopy may be helpful in distinguishing desmoplastic TE from BCC. The RCM findings in TE of keratin-filled cysts in tumor islands and attachment of the tumor to follicular structures have not been previously observed in BCC, and thus may also be diagnostically helpful. Further study is necessary for validation of these findings.

Immunohistochemical studies on cytokeratin 8 and 18 expressions in canine cutaneous adnexus and their tumors

The expressions of cytokeratin 8 and 18 (CK8 and CK18) in the normal canine skin (2 cases) and cutaneous adnexal tumors (127 cases) were investigated immunohistochemically. In the normal skin, co-expression of CK8/18 was found in the glandular epithelium of apocrine sweat glands, and single CK8-immunoreactivity was detected occasionally in the external root sheath at the isthmus and suprabulbar regions of the hair follicles. Neoplastic glandular epithelial cells in all apocrine gland tumors (21/21 cases, 100%) had co-expression of CK8/18. In trichoblastomas (27/28 cases, 96%), most neoplastic cells were diffusely positive for CK8, but those were negative for CK18. Single CK8-expression was also observed in basaloid neoplastic cells in several cases of trichoepitheliomas (7/19 cases, 37%) and pilomatricoma (1/7 cases, 14%). In several cases of trichoblastomas (4/28 cases, 14%) and trichoepitheliomas (2/19 cases, 11%), tumor cells forming glandular structures had co-expression of CK8/18. There were no positive reactions for both CK8 and 18 in infundibular keratinizing acanthomas, and sebaceous and hepatoid gland tumors. The present findings indicate that co-expression of CK8/18 is a specific feature of apocrine sweat glands and single CK8-expression represents the natures of external root sheath or pluripotential stem cells. Thus, the combination of CK8- and 18-immunostainings may have the utility to confirm the directions of differentiation in canine cutaneous adnexal tumors providing a reliable hallmark for histopathological diagnoses.

[Desmoplastic trichoepithelioma: presentation of two cases]

Trichoepithelioma is a benign neoformation with hair follicle differentiation that may clinically present in solitary, multiple or desmoplastic form. From a histopathological standpoint, it poses some diagnostic difficulties with basal cell carcinoma. We present two cases of desmoplastic trichoepithelioma, a rare adnexal tumor whose incidence is estimated at 2 per 10,000. Desmoplastic trichoepithelioma is a benign lesion, clinically and histologically similar to other dermatoses, and presents a true diagnostic challenge.

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.