Henning Hildmann

Osteoclast stimulating and differentiating factors in human cholesteatoma.

Objectives To investigate the expression of osteoclast‐activating and differentiating factors and to study the occurrence of osteoclast precursor cells and osteoclasts in acquired human cholesteatoma tissue.

Expression of a cell-cycle-associated nuclear antigen (MIB 1) in cholesteatoma and auditory meatal skin.

Middle ear cholesteatoma is often invasive with consequent bone destruction. Inflammatory stimulation of the underlying connective tissue, as well as an autocrine mechanism, may be responsible for the dys‐regulation and abnormal proliferative features of the keratinocytes in cholesteatoma. Comparative investigations were performed to assess the epithelial cell kinetics of cholesteatoma and normal auditory meatal skin. Monoclonal antibody MIB 1 immuno‐staining (which recognizes a nuclear antigen expressed by dividing cells) was applied using the alkaline phosphatase antialkaline phosphatase im‐munolabeling method.

Immunohistochemical detection of proliferating cell nuclear antigen in middle ear cholesteatoma

Cholesteatoma epithelium is characterized by a keratinocyte dysregulation accompanied by destruction of the ossicles and temporal bone. Immunohistochemical methods using antibodies to cell-cycle-related antigens can be used as a means for assessing various aspects of proliferation in cholesteatoma tissue. They also have the important advantage of preserving the spatial orientation of proliferating cells in histological sections. Proliferating cell nuclear antigen (PCNA) is a 36 kDa DNA-delta-polymerase-associated protein that is directly involved in the mechanisms of DNA synthesis. In the present study the expression of PCNA was investigated in formalin-fixed, paraffin-embedded biopsy specimens of cholesteatomas and normal skin. Normal skin revealed nuclear staining in a small number of keratinocytes (PCNA grade, 1.5) located in the basal cell layer. In contrast, an increased number of PCNA-labeled basal and suprabasal epidermal cells (PCNA grade, 9.3) were found in cholesteatoma samples. Our findings indicate that PCNA represents a reliable marker for epithelial proliferation, showing that cholesteatoma epithelium proliferates at a higher rate than normal epidermis. These findings also support the concept of keratinocyte dysregulation in middle ear cholesteatoma.

Basement Membrane in Middle Ear Cholesteatoma Immunohistochemical and Ultrastructural Observations

We investigated the distribution of basement membrane zone (BMZ) components collagen type IV, collagen type VII, and fibronectin in human middle ear cholesteatoma, auditory meatal skin, and middle ear mucosa using both immunohistochemical and ultrastructural methods. Collagen type IV inununoreactivity of skin and middle ear mucosa is continuous in the BMZ, whereas cholesteatoma frequently showed absent immunoreactivity or focal discontinuities. Collagen type VII inununoreactivity is detected similarly within the BMZ of cholesteatoma and skin. Fibronectin immunoreactivity is observed within the dermoepithelial junction of skin and middle ear mucosa. In cholesteatoma, however, fibronectin immunoreactivity is markedly increased within the extrinsic BMZ and the subepithelial connective tissue. The ultrastructural arrangement of the BMZ of cholesteatoma is like that of skin; however, it exhibits distinct alterations of the lamina fibroreticularis and lamina densa. Our results outline cholesteatoma as a disease with disturbed cell matrix interactions analogous to those of wound reepithelialization.

Zoledronic acid inhibits osteoclastogenesis in vitro and in a mouse model of inflammatory osteolysis

This study assessed effects of the bisphosphonate zoledronic acid (ZLNA) on osteoclastogenesis. To assess the effect of ZLNA on osteoclast formation in vitro, we cultured mouse bone marrow cells under conditions that promote osteoclastogenesis. Administered at concentrations from 10−6 to 10−9 mol/L, ZLNA led to a dose-dependent inhibition of osteoclastogenesis. Combined TUNEL staining and histochemical staining for tartrate-resistant acid phosphatase showed that ZLNA induced apoptosis in osteoclasts and monocytic precursor cells. To study the effects of ZLNA in vivo, we placed keratin particles onto the surface of the parietal bone of mice to induce localized inflammatory bone resorption. Three experimental groups received daily subcutaneous injections of ZLNA (1, 3, or 10 μg/kg body weight) from 4 days before surgery until 5 days after keratin implantation. The ZLNA significantly reduced osteoclast recruitment in a dose-dependent manner, but did not affect the degree of inflammation or the mineral apposition rate.

Rare tumors of the internal auditory canal

The study was performed to identify the incidence and histology of rare tumors with growth restricted to the internal auditory canal (IAC) that are different from vestibular schwannoma (VS). Furthermore, the question was addressed whether a preoperative diagnosis would be possible in these cases. A series of 351 patients that were operated on for IAC tumors through a transtemporal or translabyrinthine approach was investigated retrospectively. Cases with a tumor entity other than VS were analyzed for symptoms, radiological diagnosis, intraoperative findings and postoperative histolopatology to determine if a differential diagnosis to the common VS can be established prior to surgery. In 15 out of 351 cases (4.3%), uncommon processes of the IAC were determined by histology (6 lipomas, 3 hemangiomas, 2 neurofibromas, 2 menigiomas, 1 facial neuroma and 1 case of bilateral malignant lymphoma). The symptoms and the clinical manifestations were typical for patients with VS so that a preoperative differential diagnosis was not possible in the majority of cases. An analysis of the operation reports revealed that in 10 out of the 15 cases the surgeon suspected an unusual tumor of the IAC during surgery. The results of the present investigation suggest that rare lesions of the IAC can be expected in less than 5% of the cases and that preoperative diagnosis of rare IAC tumors is difficult. Intraoperative findings such as adhesion to cranial nerves and consistency of the tumor often indicate unusual processes, but histological analysis of the removed tissue is essential for the definite diagnosis.

Cytokeratin expression pattern in congenital and acquired pediatric cholesteatoma

Pediatric cholesteatoma can be classified as congenital or acquired based on clinical criteria. We studied the expression patterns of five distinctive cytokeratins in both types of cholesteatoma in order to improve understanding of their pathogenesis and origin. A comparable expression pattern for CK10, CK14, CK18, CK19 and 34βE12 antigens was found in the matrix of congenital and acquired pediatric cholesteatoma. Our results demonstrate that congenital and acquired pediatric cholesteatoma exhibit an identical cytokeratin distribution pattern, suggesting that they share a common origin. Therefore, it seems possible that a portion of the so-called “acquired” cholesteatoma may actually originate from advanced congenital cholesteatoma with secondary destruction of the tympanic membrane in the pediatric patient population.

Cholesteatoma in children

Cholesteatoma in children is generally considered to be more aggressive and destructive than in adults. Each otologic surgeon has experienced widely extended cholesteatomas in children with large pneumatized mastoid processes. In this paper, we want to present clinical and experimental observations which imply that the destructive potential in children is similar to that in adults. Factors and observations that have led to the assumption that cholesteatoma in children is more aggressive will be discussed. Based on our experience and the literature, we tried to distill the current and leading thoughts concerning this intriguing entity.

Immunhistochemische Untersuchungen von Mittelohrschleimhautresten im Cholesteatom

ZusammenfassungDas Cholesteatom ist durch das Einwachsen verhornenden Plattenepithels in das Mittelohr charakterisiert. Um das Verhalten beider Epithelien zu beschreiben, wurden 50 Cholesteatompräparate mit Mittelohrschleimhautanteilen immunhistochemisch auf die Expression und Lokalisation von Interleukin-1 (Il-1), „transforming growth factor-α” (TGF-α), „epidermal growth factor” (EGF), „epidermal growth factor-receptor” (EGF-R), des Proliferationsmarkers MIB 1, des Protoonkogenprodukts c-myc und des Aktivierungsmarkers 4F2 vergleichend untersucht. Die Keratinozyten des Cholesteatoms besaßen eine deutlich höhere Aktivierungs- und Proliferationsrate als die Mittelohrschleimhautzellen. Die Epithelzellen der Mittelohrmukosa zeigten immunhistochemisch keine Expression von TGF-α, EGF-R, Il-1 und c-myc, im Gegensatz zur deutlichen Immunreaktivität der Cholesteatommatrix. Die lokale Freisetzung von Zytokinen und Wachstumsfaktoren, wie TGF-α, EGF und Il-1 aus Zellen des entzündlichen Infiltrats der Perimatrix, scheinen für das hyperproliferative Wachstumsverhalten der Cholesteatommatrix von besonderer Bedeutung zu sein. Die Ergebnisse können als Erklärungsansatz für das Fortschreiten des Cholesteatomwachstums unter Verdrängung der Mittelohrschleimhaut dienen.SummaryThe development of a middle ear cholesteatoma is usually associated with chronic inflammation and displacement of the mucosa present by the invading squamous epithelium. To analyze the clinically different behaviors of both epithelia, we used immunohistochemical methods to study the distribution and expression of interleukin-1 (Il-1), transforming growth factor-alpha (TGF-α), epidermal growth factor (EGF), epidermal growth factor-receptor (EGF-R), the proliferation marker MIB 1, c-myc proto-oncogene product and activation marker 4F2. Results stromal that keratinocytes in a cholesteatoma exhibited a much higher activation and proliferation rate when compared to middle ear mucosa cells. Middle ear epithelial cells showed no immunoreactivity for TGF-alpha, EGF-R, Il-1 and c-myc in contrast to the markedly positive immunoreactivity found in cholesteatoma matrix. The local release of cytokines and growth factors, such as TGF-alpha, EGF and Il-1 by inflammatory cells seems to be an important factor for the hyperproliferative behavior of cholesteatoma epithelium. Our findings could contribute to the pathogenesis of middle ear cholesteatoma and give a possible explanation for the sustained progression of its growth leading to displacement of the middle ear mucosa.

Posterior canal wall reconstruction with a composite cartilage titanium mesh graft in canal wall down tympanoplasty and revision surgery for radical cavities

OBJECTIVES To investigate posterior external ear canal wall reconstruction with a composite cartilage titanium mesh graft in canal wall down tympanoplasty and revision surgery for open mastoids. STUDY DESIGN Retrospective case review. SETTING Tertiary referral centre. METHODS As a preliminary study, 15 selected patients underwent reconstruction of a posterior ear canal wall defect with titanium mesh. Large defects of the posterior external auditory canal wall, resulting from canal wall down tympanoplasty or present in revision surgery, were eliminated by reconstruction using a titanium mesh. The mesh was covered with conchal cartilage and attached to the cortical mastoid bone using 3-mm titanium screws. RESULTS All patients maintained a normal contour of the external ear canal, without depression, extrusion or infection. There were no failures, based on short-term post-operative controls. However, two procedures had to be revised due to incomplete coverage of the titanium mesh. CONCLUSIONS This study shows that reconstruction of the posterior ear canal wall with a composite cartilage titanium mesh is a valuable method for preserving the morphology of the external auditory canal in selected cases. Problems occurring in canal wall down tympanomastoidectomy and radical cavities may therefore be avoided. However, long-term results have yet to be evaluated.