Pseudocystic pilomatricoma: A new variant and review of the literature

A classic pilomatricoma, which usually presents with an asymptomatic, solitary, firm, subcutaneous nodule in the head, neck, or extremities of the paediatric population, is easily diagnosed based on its characteristic clinical and histopathological features. However, its variants often pose particular diagnostic challenges to clinicians due to their rarity and diverse clinicopathological features. We present a new pseudocystic variant, manifesting as solid lesions floating in a fluid‐filled sac.     

The common ultrasonographic features of pilomatricoma.

OBJECTIVES: The purpose of this series was to describe typical ultrasonographic features of 20 cases of pilomatricoma and to improve its diagnostic rate with the use of an ultrasonographic approach. METHODS: For 20 pilomatricomas in 19 patients with preoperative ultrasonography from 1995 to 2004, we reviewed age, sex, symptoms, duration, referring clinician, and tumor sites. The ultrasonographic findings were retrospectively analyzed for tumor location, shape, size, margin, echo texture, echogenicity, presence, amount, and shape of calcification, presence of a hypoechoic rim, and Doppler flow pattern. RESULTS: The mean age of the 19 patients was 6.9 years (range, 1-21 years), and the female-male ratio was 1.1:1. Patients had a painful palpable mass in 10 cases (50%). Nine lesions occurred in the neck, 5 in the cheek, 2 in the preauricular region, and 4 in the extremity. All tumors were located in the subcutaneous layer. The mean size of the tumors was 13.4 mm. Fourteen pilomatricomas (70%) appeared as well-defined oval masses. Tumors were heterogeneously hyperechoic in 80% of cases. All tumors had internal echogenic foci. A hypoechoic rim was seen in 17 cases (85%). Doppler flow signals were observed in the peripheral region in 14 cases (70%). A correct preoperative diagnosis was made in 33% on the basis of clinical findings and in 76% by ultrasonography. CONCLUSIONS: Diagnosis of pilomatricoma should be considered when a well-defined mass with inner echogenic foci and a peripheral hypoechoic rim or a completely echogenic mass with strong posterior acoustic shadowing in the subcutaneous layer of the head, neck, or extremity is found on ultrasonography.     

Atypical adult non-calcified pilomatricoma

We present a rare case of a non-calcified pilomatricoma in a 67-year-old man. This tumor was extremely large in size, and its location, in the lower extremity, was very unusual. The clinical, radiographic, and histopathological features are described in detail. The role of magnetic resonance imaging (MRI) in the diagnosis of this entity is discussed. Definite internal reticulations and septations were observed. A possible explanation for this observation is that the high signal intensity reticulations may represent edematous stroma surrounding basaloid cells. Received: 8 July 1999 Revision requested: 28 July 1999 Revision received: 10 September 1999 Accepted: 13 September 1999     

Perforating pilomatricoma: transepithelial elimination or not

We present a 56-year-old woman with a perforating pilomatricoma in the left eyebrow region. Histologically, the tumor consisted mainly of basophilic cells and shadow cells, and the tumor components were being eliminated through an ulcer with damage to the epithelial structures. In past reports of perforating pilomatricoma, this elimination pattern has often been described as transepithelial elimination. In many patients with perforating pilomatricoma, elimination is accompanied by ulceration and epithelial damage. Mehregan recently stated that elimination accompanied by epidermal necrosis and superficial ulceration constituted one form of transepithelial elimination. Epidermal necrosis and ulceration generally constitute severe damage. However, when Mehregan first proposed the concept of transepithelial elimination, it was defined as a phenomenon with relatively little or no damage to the epithelial structures, differentiating it from other types of elimination. This original definition makes transepithelial elimination a unique and interesting phenomenon, and its most important feature is that there is relatively little or no damage to the epithelial structures. Therefore, the terms "epidermal necrosis" and "ulceration" should not be used in association with transepithelial elimination. Hence, in patients with perforating pilomatricoma, the elimination of tumor components from ulcers with damage to the epithelial structures, as seen in the present case, should not be described as transepithelial elimination.     

皮肤钙化上皮瘤的临床病理分析

目的：研究皮肤钙化上皮瘤的临床及组织病理特点。方法：回顾性研究我院1980-2002年27例钙化上皮瘤的临床病理资料。结果：其中70．19％的病例发病年龄在30岁以下，男女比例为l：2；好发于面、颈及上肢等部位，肿瘤直径为0．3-3．0cm。77．78％的病例临床分别误诊为皮脂腺囊肿、表皮囊肿及皮肤纤维瘤等；70．37％的肿瘤有包膜，由影子细胞及嗜碱性细胞组成，间质中有不同程度的钙化和炎细胞浸润。结论：钙化上皮瘤具有多样化的临床表现，易误诊，对面、颈及上肢皮肤单发的质硬结节，应考虑到钙化上皮瘤的可能。     

Inverted malignant pilomatricoma of the neck

Malignant pilomatricoma is an uncommon malignant follicular adnexal tumor with a predilection for the head and neck among older males. We report the case of a male with an inverted malignant pilomatricoma of the left neck. The initial diagnostics and the treatment pointed to carcinoma of unknown primary (CUP syndrome). The preoperative diagnostic tests included ultrasound examination, CT scan and fine-needle aspiration cytology. However, the preoperative diagnostics did not provide any further information, leading to doubts concerning the initially proposed diagnosis. Histology of the resected tumor revealed a malignant pilomatricoma. We report the clinical presentation and the management of this case and discuss the clinical and histological findings.     

PILOMATRICOMA IN CHILDREN: A Frequently Misdiagnosed Superficial Tumor

Pilomatricomas are the most common superficial tumors in children, but they are frequently misdiagnosed preoperatively. There are some characteristic features of pilomatricomas that can help clinicians differentiate it from other tumors. The authors report 3 children with head and neck pilomatricomas, one with multiple tumors. They emphasize some clinical features that may help in differential diagnosis to avoid unnecessary investigations before surgical removal.     

Malignant pilomatricoma in the parietal area

A 27-year-old Japanese woman presented with a 2.5-cm nodular subcutaneous lesion in the parietal area. The nodule was well demarcated and situated in the dermis and subcutis. Histologically, the tumor was diagnosed as malignant pilomatricoma. The tumor was excised, the postoperative course was uneventful, no evidence of local recurrence or distant metastasis was observed, and the patient continues to be under close follow-up. Malignant pilomatricoma, a locally aggressive counterpart of benign pilomatricoma, is also referred to as pilomatrix carcinoma. Most cases are excised as benign tumors; however, when the excision is incomplete local recurrence is likely, and distant metastases have also been reported. Histologically, the diagnosis can be challenging because no clear histologic criteria are available. Because of the rarity of malignant pilomatricoma, no welldefined standards in the surgical management of this neoplasm have been established. Moreover, since distant metastases have been described, close followup of the lesion is requisite.