A Revaluation of Folliculosebaceous Cystic Hamartoma: The Histopathological and Immunohistochemical Features

Giant Folliculosebaceous Cystic Hamartoma of the Face

Folliculosebaceous cystic hamartoma (FSCH) is a rare and benign form of cutaneous hamartomas. These skin lesions often lead to clinical and histopathological misdiagnosis due to their similarities to cutaneous lesions with overproduction of clustered sebaceous glands. Clinically, the lesions often present as solitary, skin-colored, pedunculated warts to cauliflower-like, exophytic papules and nodules, usually with a diameter ranging 0.5-1.5 cm that rarely exceed 2 cm in size. Only a small number of giant variants are reported in the literature with a diameter in the range of 5-23 cm. The vast majority of the lesions appear in the central face and show a striking predilection for the nose, ears, and scalp, but also emerge on the nipples, extremities, and genitals. Histologically, the epithelial components of folliculosebaceous cystic hamartoma comprise dilated infundibular cystic proliferation with surrounding mesenchymal components, which commonly include fibroplasia and vascular and adipose tissue proliferation. These histological characteristics were coined by Kimura and colleagues (1991). To the best of our knowledge, our case represents the biggest variant of giant folliculosebaceous cystic hamartoma.

Folliculosebaceous Cystic Hamartoma with Spindle Cell Lipomatous and Neural Components

Folliculosebaceous cystic hamartoma is a cutaneous malformation composed of a cystic folliculosebaceous structure associated with mesenchymal elements, generally consisting of fibrous stroma, adipocytes and small vascular channels. We report the case of a 55-year-old female patient with a cutaneous nodule of the right nasal wing. Microscopically, the lesion showed a dilated hair follicle with multiple sebaceous glands, surrounded by a mesenchymal component composed of fibromyxoid stroma, spindle cells, mature-appearing adipocytes and collagen bundles, resembling spindle cell lipoma, associated with an additional neural component, consisting of small nerve bundles. In folliculosebaceous cystic hamartoma, the association of spindle cell lipomatous and neural components has not previously reported.

Folliculosebaceous Cystic Hamartoma Arising in Miescher-Type Melanocytic Nevi

ABSTRACT

Folliculosebaceous cystic hamartoma (FSCH) is a rare cutaneous hamartoma consisting of dilated folliculosebaceous units associated with mesenchymal elements. Ansai et al reported that distinctive features of Miescher-type melanocytic nevi (MMCNs) accompanied 4.6% of FSCH; however, there have been no data about how often FSCH features accompany MMCNs. In this study, we used 7829 cases that had been histopathologically diagnosed as MMCNs of the face, neck, and scalp at the Department of Dermatopathology, Nippon Medical School Musashi Kosugi Hospital and observed whether features of FSCH accompanied them. Of the resected MMCNs, 274 of 7829 (3%) were accompanied by features of FSCH. The nose was the most common resection site, followed by the eyebrow area, ear, and cheek. The coexistence rate for the nevi on the nose and features of FSCH was as high as 10%-20%, and its rate increased with age. We found that FSCH appears mostly in seborrheic areas, such as the nose and cheek, which are rich in normal sebaceous glands. This suggests that nevi, especially on and around the nose, may induce FSCH or similar lesions.

Genital Folliculosebaceous Cystic Hamartoma: A Case Report and Concise Review of the Literature

Folliculosebaceous cystic hamartoma (FSCH) is an uncommon hamartoma that usually presents on the central face area of adults as an asymptomatic, solitary dome-shaped or pedunculated papule. We report a case of a 35-year-old female who presented with six-months history of skin lesions on her labia majora. Histological findings included cystically dilated hair follicles with branching epithelial strands and interconnecting sebaceous gland consistent with the diagnosis of FSCH. The genital variant of FSCH was first described in 1998 and since then only six cases have been reported in the literature. We aim to increase awareness of this rare presentation due to the significant psychological implications and the risk of misdiagnosis.

Therapeutic implications of immunohistochemical expression pattern of the cancer stem cell marker (nestin) in basal and squamous cell carcinomas

Cancer stem cells (CSC) are populations of cells responsible for tumor initiation, progression and therapeutic resistance in many cancers. In the present study, we aimed to investigate the expression pattern and clinical significance of the stem cell marker nestin, in Squaous cell carcinoma (SCC) and basal cell carcinoma (BCC). The samples (23 cases of BCC and 22 cases of SCC) were immunohistochemically examined for the expression of nestin and its correlation with the corresponding clinical and pathological parameters. Nestin was expressed in four out of the 23 cases of BCC (17.4%) and was expressed in 10 out of the 22 cases of SCC (45.5%). Nestin expression between the two tumors was statistically significant (P = .042). Although a direct relationship was found between the tumor grade and nestin expression, the results were statistically insignificant (P = .495). The results of this study suggest that BCC and SCC may share some cellular origin but with different biologic behavior. The relation of nestin expression to the grade of SCC, although statistically insignificant, may suggest its role in predicting the biologic behavior of this tumor.

Intraoral Cutaneous Hamartomas-Clinicopathologic and Immunohistochemical Characteristics of 3 Cases

Intraoral cutaneous hamartomas (ICHs) are uncommon mucosal lesions characterized microscopically by a combination of cutaneous structures, including various stages of follicular and sebaceous elements. Due to their rarity, the clinicopathologic and immunohistochemical attributes of ICHs have not been thoroughly delineated. Three cases of ICH were identified from our records, and formalin-fixed paraffin-embedded sections were immunohistochemically stained with antibodies against androgen receptor, estrogen receptor, and progesterone receptor, p63, factor XIIIα, and CD34. All 3 ICHs involved the buccal mucosa with an M:F ratio = 2:1 and mean age = 42.3 years (age range: 27-61 years). ICHs presented as thickened, painless, white and yellow plaques or nodules of long duration, measuring 0.6-1.5 cm. No history of skin graft in the area of the lesions was reported. Histopathologically, the lesions showed aggregates of rudimentary folliculosebaceous structures. Although well-defined piloerector muscles were present in all cases of ICH, bona fide hair follicles and isolated hair shafts were identified only in 1 case. The overlying oral epithelium exhibited epidermis-like morphological features, while inflammation was generally absent. Immunohistochemically, strong and diffuse nuclear staining for androgen receptor and factor XIIIα was observed in the sebaceous glands, and estrogen receptor and p63 reactivity were confined exclusively to the peripheral basal cells, while progesterone receptor staining was negative in ICHs. CD34 diffusely decorated the lesional stroma. In conclusion, ICH is a rare lesion composed of cutaneous elements in an abnormal location. A predilection for the buccal mucosa is reported in the current study.

Hamartomas of skin and soft tissue

Hamartomas are benign lesions composed of aberrant disorganized growth of mature tissues. Choristomas are similar, except that they are composed of tissues not normally found at the anatomic site in which the lesion is arising. A wide range of hamartomas and choristomas can arise in the skin and soft tissue. Some of these may cause diagnostic difficulty and potentially be mistaken for neoplasms. Some neoplasms may resemble hamaratomas. Here we review the current clinical and pathologic features of these lesions, both common and rare, and discuss how to distinguish them from other entities in the differential diagnosis.

Intracranial epidermoid cyst with proliferative folliculosebaceous epithelium: Report of a rare case and discussion on pathogenesis

Intracranial epidermoid cysts are rarely known to increase in size over a brief period. While malignant transformations of epidermoid cyst have been previously described, no reports to date have described rapid proliferation accompanied by mature hair follicles and sebaceous glands without malignant transformations. The present case involved a 71-year-old man who visited a local physician with disturbance of equilibrium. A mass lesion was detected at the left cerebellopontine angle and was subsequently removed. Histopathological diagnosis of this lesion was as an epidermoid cyst. Seventeen years after this initial surgery, worsened left hypoacusis, disorientation, eating disorder and gait disturbance appeared, and the patient visited the physician again. Local recurrence of the lesion was observed, and the patient was referred to our hospital for its removal. Intraoperative findings revealed a pearly white tumor, histopathologically diagnosed as an epidermoid cyst. Three years later, local recurrence was observed, and the cyst was again removed. Intraoperative findings revealed a partially pearly white tumor similar to the tumor observed during the second surgery, but the majority of the tumor was non-shiny, ochre-colored and suckable. Histopathological diagnosis was an epidermoid cyst with an epidermis-like structure. Postoperative activities of daily living were independent thereafter, but from March of the following year, he began to experience increasing difficulty in walking and subsequently visited our hospital again. Tumor recurrence was observed and was removed again in November of the same year. Intraoperative findings revealed a tumor that was primarily ochre-colored, non-shiny, brittle and suckable. The histopathological diagnosis was folliculosebaceous epithelial proliferative lesion accompanied by an epidermis-like epithelium and a differentiation into hair follicles and sebaceous gland,s and the tumor was determined to be an epidermoid cyst with proliferative folliculosebaceous epithelium.

Chronological changes in trichofolliculoma: Folliculosebaceous cystic hamartoma is not a very-late-stage trichofolliculoma

Some authors have reported that the secondary hair follicles in trichofolliculomas (TF) undergo regressive changes and are subsequently replaced by the developed sebaceous elements, and that folliculosebaceous cystic hamartoma (FSCH) is a TF at a very late stage. In the present study, we revaluated the histopathological features of 40 TF lesions, focusing on their chronological changes. The results of the present study indicate that while the secondary follicles in the TF exhibited the hair cycle, the normal hair cycle was out of control, and tertiary hair follicles randomly developed from the involuting secondary follicles. The repeated development of hair follicles in this disordered hair cycle caused the development of chains of several continuous hair follicles in late-stage TF. In the TF lesions, no features indicating the replacement of the regressing secondary hair follicles by any sebaceous elements were observed, thereby suggesting that FSCH is not a very-late-stage TF.

Folliculosebaceous Cystic Hamartoma With Spindle Cell Lipoma-Like Stromal Features

Folliculosebaceous cystic hamartoma is a distinctive cutaneous hamartoma composed of follicular, sebaceous, and mesenchymal components. The lesions are most commonly found on the face and scalp of young adults, with approximately 30% occurring in the nasal or paranasal regions of the face. The clinical differential diagnoses are extensive and include epidermoid cyst, dermal nevus, soft fibroma, and adnexal tumors including sebaceous neoplasms. Here, the authors present a case of a 24-year-old man who presented for evaluation of an asymptomatic growth on the nose, which had slowly enlarged over 9 years. On examination, there was a 0.6 cm dome-shaped flesh-colored papule on the nasal bridge. The clinical differential included dermatofibroma versus intradermal nevus. A shave biopsy was performed, and histological examination of the sections showed a proliferation of multiple enlarged and irregular-appearing sebaceous glands attached to a cystic follicular structure. The associated dermal mesenchymal component consisted of numerous mature-appearing adipocytes associated with a fibromyxoid stroma, prominent collections of mucin, and bundles of ropey collagen resembling a spindle cell lipoma. This combination of a folliculosebaceous cystic hamartoma with a spindle cell lipoma-like mesenchymal proliferation is unusual and has not been previously reported.

Benign follicular tumors

Benign follicular tumors comprise a large and heterogeneous group of neoplasms that share a common histogenesis and display morphological features resembling one or several portions of the normal hair follicle, or recapitulate part of its embryological development. Most cases present it as clinically nondescript single lesions and essentially of dermatological relevance. Occasionally, however, these lesions be multiple and represent a cutaneous marker of complex syndromes associated with an increased risk of visceral neoplasms. In this article, the authors present the microscopic structure of the normal hair follicle as a basis to understand the type and level of differentiation of the various follicular tumors. The main clinicopathological features and differential diagnosis of benign follicular tumors are then discussed, including dilated pore of Winer, pilar sheath acanthoma, trichoadenoma, trichilemmoma, infundibuloma, proliferating trichilemmal cyst/tumor, trichoblastoma and its variants, pilomatricoma, trichodiscoma/fibrofolliculoma, neurofollicular hamartoma and trichofolliculoma. In addition, the main syndromes presenting with multiple follicular tumors are also discussed, namely Cowden, Birt-Hogg-Dubé, Rombo and Bazex-Dupré-Christol syndromes, as well as multiple tumors of follicular infundibulum (infundibulomatosis) and multiple trichoepitheliomas. Although the diagnosis of follicular tumors relies on histological examination, we highlight the importance of their knowledge for the clinician, especially when in presence of patients with multiple lesions that may be the cutaneous marker of a cancer-prone syndrome. The dermatologist is therefore in a privileged position to recognize these lesions, which is extremely important to provide further propedeutic, appropriate referral and genetic counseling for these patients.

Folliculosebaceous cystic hamartoma of the external auditory canal in an adult

Folliculosebaceous cystic hamartoma (FSCH) is a cutaneous hamartoma of pilosebaceous origin that usually occurs on the face. We present what we believe is only the second reported case of FSCH of the external auditory canal, and the first in an adult. The patient was a 59-year-old woman who presented with a 4-year history of a firm nodule on the left external auditory canal that had caused hearing loss, pruritus, and pain. The lesion was excised, and histopathologic examination identified infundibular cysts, hyperplasia of the sebaceous lobules, and a large amount of mucin, features that are consistent with FSCH. One year postoperatively, the patient was asymptomatic, and no evidence of recurrence was noted.

Nuclear survivin expression as a potentially useful tool for the diagnosis of canine cutaneous sebaceous lesions

BACKGROUND

Sebaceous glands are specialized cutaneous adnexal glands, which work under constant hormonal control to produce sebum. They can give rise to several proliferative lesions, such as hamartoma, hyperplasia and neoplasms (adenoma, epithelioma and carcinoma). Their nomenclature is currently confusing, both in veterinary and in human medicine, owing to the difficulty of differentiating between some of these lesions.

METHODS

The present study used immunohistochemistry to determine the expression levels and patterns of survivin and Ki67 in five samples of normal canine skin and 44 cases of canine cutaneous lesions with sebaceous differentiation (10 hamartomas, nine hyperplasia, eight adenomas, eight epitheliomas and nine carcinomas).

RESULTS

In normal glands, survivin, as well as Ki67, was expressed in scattered reserve cells. In hamartomas, survivin was more highly expressed than in normal skin, indicating a possible role of this molecule in the pathogenesis of these congenital lesions. In tumours, a moderate or high level of survivin and Ki67 expression (more than two and four and more than two positive cells, respectively) were significantly correlated with a malignant histotype, infiltrative growth and a moderate or high number of mitoses (more than two).

CONCLUSIONS AND CLINICAL IMPORTANCE

The level of survivin expression increased with increasing malignancy, designating survivin as a new diagnostic marker in the assessment of malignancy of sebaceous tumours.

Inhibition of BMP signaling in P-Cadherin positive hair progenitor cells leads to trichofolliculoma-like hair follicle neoplasias

BACKGROUND

Skin stem cells contribute to all three major lineages of epidermal appendages, i.e., the epidermis, the hair follicle, and the sebaceous gland. In hair follicles, highly proliferative committed progenitor cells, called matrix cells, are located at the base of the follicle in the hair bulb. The differentiation of these early progenitor cells leads to specification of a central hair shaft surrounded by an inner root sheath (IRS) and a companion layer. Multiple signaling molecules, including bone morphogenetic proteins (BMPs), have been implicated in this process.

METHODS

To further probe the contribution of BMP signaling to hair follicle development and maintenance we employed a transgenic mouse that expresses the BMP inhibitor, Noggin, to disrupt BMP signaling specifically in subset of hair follicle progenitors under the control of neuron specific enolase (Nse) promoter. We then studied the skin tumor phenotypes of the transgenic mice through histology, immunohistochemistry and Western Blotting to delineate the underlying mechanisms. Double transgenic mice expressing BMP as well as noggin under control of the Nse promoter were used to rescue the skin tumor phenotypes.

RESULTS

We found that the transgene is expressed specifically in a subpopulation of P-cadherin positive progenitor cells in Nse-Noggin mice. Blocking BMP signaling in this cell population led to benign hair follicle-derived neoplasias resembling human trichofolliculomas, associated with down-regulation of E-cadherin expression and dynamic regulation of CD44.

CONCLUSIONS

These observations further define a critical role for BMP signaling in maintaining the homeostasis of hair follicles, and suggest that dysregulation of BMP signaling in hair follicle progenitors may contribute to human trichofolliculoma.

[Folliculosebaceous cystic hamartoma: anatomo-clinical study]

BACKGROUND

Folliculosebaceous cystic hamartoma (FSCH) is a relatively recently described malformation with follicular and sebaceous components and a particular type of stroma with adipocytes. We conducted an anatomo-clinical study in order to clarify the clinical and histological characteristics of FSCH.

MATERIALS AND METHODS

We included all cases of FSCH diagnosed between 1985 and February 2011 at our dermatopathology laboratory. Clinical information was obtained from medical records and requests for histological examination.

RESULTS

We studied 25 cases of FSCH in 25 patients of mean age 51 years. The sex ratio was 1.3. The mean disease duration was 9 years. Lesions were described mainly as flesh-colored, occasionally pedunculated nodules and were found primarily on the face (60%). The diagnosis of FSCH had never been mentioned by the clinician. Histological examination revealed in all cases one or more follicular cystic structures surrounded by sebaceous glands in a stroma containing adipocytes. A number of variants were identified, such as the presence of a mucinous stroma, a neuroid component with protein S 100 expression, and rudimentary hair follicles in adjacent dermis. One case involved a proliferating cyst while another was on the scalp in the area of pre-existing radiodermatitis. Only one relapse was noted, 5 years after the initial excision.

DISCUSSION

FSCH is a benign, underdiagnosed lesion, localized on the face, particularly on the nose. It is dome-shaped or pedunculated and grows slowly. Differential diagnoses include nevus lipomatosus superficialis and "sebaceous" trichofolliculoma. FSCH can be readily identified by the presence of adipocytes and a fibrous stroma. One case was unique in its appearance of a large pedunculated nodule with a proliferating cyst. Prior to the invidualization of this entity, such cases were interpreted as nevus lipomatosus superficialis or "sebaceous" trichofolliculoma, although their histological appearance was inconsistent with such a diagnosis.

A clinicopathologic study of folliculosebaceous cystic hamartoma

Folliculosebaceous cystic hamartoma (FSCH) is a distinctive cutaneous hamartoma of follicular, sebaceous, and mesenchymal components. Only 70 cases of FSCH have been reported in the literature since the original report of 5 cases in 1991. There has been little information reported about the clinicopathologic characteristics of FSCH. We summarize the clinicopathologic features of 153 cases of FSCH that were diagnosed histopathologically at Sapporo Institute for Dermatopathology. The 153 cases of FSCH comprised 92 male and 61 female patients. The typical clinical presentation of FSCH revealed solitary and skin-colored, protruding papules or nodules measuring several millimeters in diameter on the face, especially on the nose, of middle-aged or older persons. These cases fulfilled the common denominators for the histopathologic diagnosis of FSCH as Kimura et al reported. Seven of 153 cases (4.6%) were accompanied by distinctive features of Miescher-type melanocytic nevi. All 7 cases showed lesions on face, especially on or around the nose. We consider that Miescher-type melanocytic nevi play a significant role in the pathogenesis of FSCH, at least in some cases.