MR imaging of a pilomatrixoma

Pilomatrixoma of the Arm: A Case Report and Review of Literature

Pilomatrixoma (PMX), also known as calcifying epithelioma of Malherbe, is a rare benign neoplasm that arises from the hair matrix cells, commonly in the head, neck, and upper trunk regions, infrequently affecting upper and lower extremities. It has to two peaks of presentation: under 20 years of age or between 50 and 65 years of age, slightly more common in females. The neoplasm exhibits diverse clinical manifestations and is frequently subject to misdiagnosis with alternative dermatological diseases. We present an atypical case of PMX affecting the upper extremity of a 62-year-old female patient. Surgical removal of the affected tissue under local anesthesia was performed, and subsequent histopathological analysis confirmed the presence of PMX. Based on the literature search we performed, we found out that this pathology is underreported in Jordan, with only one study published describing this tumor in the maxillofacial region. Physicians should be aware of this condition and its different presentations to include it in the differential diagnosis of suspected cases to provide the appropriate management and follow-up.

Multiple pilomatrixomas: Case report and literature review

Pilomatrixoma is a rare, benign, circumscribed, calcifying epithelial neoplasm that is derived from hair matrix cells. Multiple pilomatrixomas are uncommon. We describe a case of multiple pilomatrixomas in a 23-year-old black woman who presented with lesions on her face and back. Based on the results of the clinical examination, she was provisionally diagnosed with either calcified sebaceous cysts or calcified lymph nodes. She underwent surgical excision of the masses. On histopathology, the lesions were identified as pilomatrixomas. We attribute our original failure to diagnose this condition to our lack of familiarity with it. We discuss the presentation, differential diagnosis, and other characteristics of pilomatrixomas.

MR imaging findings of pilomatricomas: a radiological-pathological correlation

BACKGROUND

Magnetic resonance imaging (MRI) findings of pilomatricomas have yet to be determined.

PURPOSE

To assess the correlation between MRI and pathological findings of pilomatricomas.

MATERIAL AND METHODS

MR images were obtained on patients with histologically proven pilomatricomas using a 1.5-T MR scanner. The images were retrospectively reviewed for size, signal intensity compared with skeletal muscles, and enhancement patterns. Furthermore, we assessed the presence of a reticular appearance, a ring-like appearance, and peritumoral fat stranding.

RESULTS

We included 11 consecutive patients with 12 histologically proven pilomatricomas (3 boys/men, 8 girls/women; age range, 4-76 years; mean age, 20 years; median age, 14 years). The tumors were located in the head and neck (n = 6), upper extremities (n = 5), and lower extremities (n = 1). The maximum tumor diameter was in the range of 7-32 mm (mean, 16.5 mm). On T2-weighted (T2W) images, five tumors showed homogeneous hypointensity, whereas six showed reticular hyperintensity and one showed cystic hyperintensity. On fat-suppressed T2W images, nine tumors showed reticular hyperintensity, eight showed ring-like hyperintensity, and five showed peritumoral fat stranding. On fat-suppressed gadolinium-enhanced T1-weighted (T1W) images, one tumor showed no enhancement, whereas three showed reticular enhancement and five showed ring-like enhancement. Histologically, edematous and fibrous stroma was observed in 10 tumors, tumor capsules in 11, and inflammatory cell infiltration of the peritumoral fat tissue in nine.

CONCLUSION

MRI features of pilomatricomas included reticular and ring-like hyperintensities on fat-suppressed T2W images and reticular and ring-like enhancement on fat-suppressed gadolinium-enhanced T1W images.

Uncommon benign tumour of the skin: infraorbital pilomatricoma

Pilomatricoma is a relatively rare tumour of the skin derived from primitive basal cells of epidermis that differentiate into hair matrix cells. It comprises approximately 1% of all benign skin tumours. The most common sites for pilomatricomas are the head, neck and upper extremities. A 44-year-old woman, admitted to our department, underwent an orthopantomography examination, which revealed a well-circumscribed 1.6×1.4 mm radiopaque mass superimposed between the medial wall of the right maxillary sinus and lateral wall of the nasal cavity. Clinically, it was firm and mobile, and remained attached to the underlying skin when palpated. A cone beam CT scan was performed to ascertain its location and anatomic relations. Subsequently, it was totally excised under local anaesthesia. Histopathological evaluation of the lesion reported it to be a pilomatricoma.

Pilomatricoma of the male breast: sonographic mammographic MRI features with pathologic correlation

We report a case of 43-year-old man who presented with an enlarging, painless, palpable mass in the left breast for one year associated with surface blue discoloration of the skin. Mammogram showed a well-defined 2.3-cm mass with microcalcifications. Ultrasound revealed a well-defined, subcutaneous hypoechoic mass adherent to the skin with multiple bright foci. Ultrasound-guided needle biopsy produced a dark-colored sample corresponding to pilomatricoma on final pathology. Bilateral breast magnetic resonance imaging showed heterogeneously hyperintense in T1- and T2-weighted images with heterogeneous enhancement toward the delayed phase. Surgical resection was carried out with wide margins.

Pediatric parotideomasseteric pilomatrixoma in children

AIMS

To review definitive histological diagnoses of patients with great salivary gland tumors with focus on the relatively high incidence of pediatric pilomatrixomas. The authors focus on clinical investigation, imaging methods and fine needle aspiration cytology of pilomatrixomas.

METHODS

We treated 12 children with great salivary gland masses aged from 6 months to 18 years from 1995 to 2010. The records of these patients were reviewed to determine sex, age, clinical presentation, and histological findings.

RESULTS

Among children having true neoplasms, there was a prevalence of carcinomas (6 out of 9), with low-grade mucoepidermoid and acinic cell carcinomas (two each) as the dominating histopathological diagnosis. There was one adenoid cystic carcinoma and one curious undifferentiated carcinoma in a 6 month old baby. Among all 6 benign lesions, accounting for a half of the total, pilomatrixoma was the most common (2 out of 6) diagnosis, representing 17% (2 out of 12) of all salivary gland lumps and 66% (2 out of 3) of all true benign neoplasms.

CONCLUSIONS

Pilomatrixoma should be included in the differential diagnosis of pediatric parotideomasseteric lumps. Clinical investigation reveals adherence to the skin but not to the underlying tissue. Clinical assessment and ultrasound guided fine needle aspiration cytology in typical findings strongly support the diagnosis. Cytopathologists must be aware of the preliminary diagnosis of a pilomatrixoma to use proper fixation of the smears. In doubts, frozen biopsy must be sent before parotidectomy is performed.

A 5-year-old girl with an enlarging mass at the elbow

Pilomatrixoma is a rare benign neoplasm that presents as a solitary, hard, mobile, subcutaneous mass. Pilomatrixomas can be found on any hair-bearing region of the body, with the upper extremity being the second most common location. Pilomatrixomas are common in children, and have a higher frequency in girls. We present a case of left-arm pilomatrixoma in a 5-year-old girl. Surgical excision was curative. Pediatric orthopedic surgeons should be familiar with this benign tumor when evaluating a calcified soft-tissue mass in the extremities of a child.

Magnetic resonance imaging of a cystic pilomatricoma in an ankle joint

Pilomatricoma, also known as calcifying epithelioma of Malherbe, is an asymptomatic, slow-growing, benign dermal neoplasm that originates from hair cortex cells. The most common sites are the head and neck (68.2%), followed by the trunk (14.4%) and the upper (15.3%) and lower (2%) extremities. The majority (60%-70%) of tumors develop in the first 2 decades of life. A typical pilomatricoma presents as a firm, calcified, dermal nodule appearing as a solid mass in subcutaneous tissue on computed tomography or magnetic resonance imaging.This article describes the case of a 42-year-old man who presented with nontender soft tissue swelling in the right ankle joint. Radiographs and magnetic resonance imaging findings showed an inflamed cystic mass with calcification in the lateral malleolar area of the right ankle joint. These atypical magnetic resonance imaging features around the ankle joint led to confusion with other disease entities, including chronic bursitis, pigmented villonodular synovitis, rheumatoid nodules, and gout. After complete excision of the mass, histological examination revealed a cystic pilomatricoma.Although rare, a cystic pilomatricoma should be considered in the differential diagnosis of soft tissue masses with calcification.

Soft tissue tumours: imaging strategy

Vascular tumours and malformations, fibrous and fibrohistiocytic tumours and pseudotumours are the most common benign soft-tissue masses observed in children, and can be treated conservatively. Rhabdomyosarcomas are the most frequent malignant tumours, accounting for about half of soft tissue sarcomas. A child referred for a soft-tissue mass should ideally be managed by a multidisciplinary team and primary excision should be proscribed until a definite diagnosis has been established. Clinical examination, conventional radiography and US with Doppler represent the first-line examinations and are sometimes sufficient to make a diagnosis. In all other situations, MRI is mandatory to establish the aggressiveness and extension of the tumour. This technique provides the relevant data to guide the decision regarding tissue sampling.

Epithelioma of Malherbe: new ultrasound patterns

Backround

Calcifying epithelioma of Malherbe, or Pilomatricoma, is considered an uncommon cutaneous neoplasia, normally occurring in children as a solitary, firm, asymptomatic, hard, subcutaneous, slowly growing nodule on the face, neck, or proximal upper extremity. In literature, two Pilomatricoma ultrasound patterns are described: the totally calcified nodule and the hypoechoic nodule with internal calcific foci. High frequency ultrasound has not yet been applied for routine diagnosis of Pilomatricoma. The aim of the study was to retrospectively identify specific ultrasound features.

Methods

We retrieved 124 histologically Pilomatricoma cases: 28 patients with 32 lesions were preoperatively evaluated with ultrasound.

Results

22/32 have shown a solid formation, hypoechoic, with a sharp outline. Of these 22, 10 lesions were completely calcifying and 12 partially calcified. In 3/32 lesions with uncertain diagnosis, ultrasounds showed a complex/mixed pattern with pseudo-fluid areas and microspots. 7/32 lesions with US different diagnosis included 3 complex lesions, 2 cystic lesions and 2 solid nodular lesions.

Conclusion

In addition to well-known ultrasound patterns (completely calcified and partially calcified) we identified three new, not yet described, patterns that constitute the 31% of the cases: complex, pseudocistyc and pseudotumoral.

MR imaging manifestations of skin tumors

In this study, we evaluated MR imaging findings of skin tumors and categorized them into four types: (1) discrete mass lesions of the dermis and epidermis, (2) mass lesions of the subcutis with or without abutment to the skin, (3) diffuse or localized skin thickening without a true mass, and (4) a skin mass with bone destruction. The categorization of MR images may be useful in the differential diagnosis of skin tumors.

Pilomatricomas in children: imaging characteristics with pathologic correlation

BACKGROUND

Although pilomatricoma commonly occurs in children, there is still a poor understanding of the imaging characteristics of pilomatricoma and lack of agreement regarding its imaging findings and histopathologic features.

OBJECTIVES

To characterize the radiologic appearance of pilomatricomas on US, CT, and MR and to correlate the imaging findings with histopathologic features.

MATERIALS AND METHODS

The imaging findings of 47 pilomatricomas on US (n = 17), CT (n = 31), and MR (n = 5) were retrospectively evaluated. Pathologic specimens of all cases were reviewed and compared with imaging findings.

RESULTS

All lesions were well-circumscribed, subcutaneous nodules with partial attachment to the overlying skin. On US, the lesions were mostly hyperechoic with posterior acoustic shadowing and hypoechoic rim. On CT, they appeared as enhancing soft-tissue masses with varying amounts of calcification. MR findings were internal reticulations and patchy areas on T2-weighted images and contrast-enhanced T1-weighted images, corresponding to edematous stroma on pathology. Peritumoral inflammatory changes and connective capsule on pathology were well correlated with imaging findings.

CONCLUSION

Pilomatricoma should be considered when US or CT shows a well-defined hyperechoic or calcific nodule in subcutaneous fat attached to the skin in children. MR images may be helpful in diagnosis. Pathologic findings are well correlated with imaging findings.

Imaging and diagnostic strategy of soft tissue tumors in children

The diagnosis of a soft tissue mass in children is a common clinical situation. Most of the lesions are benign and can be treated conservatively or by non-mutilating surgery. Nevertheless, the possibility of a malignant soft tissue tumor must be systematically considered. The most frequent benign soft tissue lesions in children are vascular lesions, fibrous and fibrohistiocytic tumors and pseudotumors, whereas rhabdomyosarcomas account for 50% of all soft tissue sarcomas. A child presenting an atypical soft tissue mass should be managed by a multidisciplinary centre, and primary resection must be proscribed until a definite diagnosis has been established. The role of imaging is essential either to confirm the benign nature of the mass or to give arguments to perform a diagnostic biopsy. Clinical examination, conventional radiography and ultrasound with Doppler represent the first-line examinations and are sometimes sufficient to assess a diagnosis. In all other situations, MRI is mandatory to establish the probable nature of the lesion and to assess local extension.

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.

Pilomatrixoma:

Pilomatrixoma, also known as calcifying epithelioma of Malherbe, is a benign skin neoplasm that arises from hair follicle matrix cells. Pilomatrixoma is a common skin neoplasm in the pediatric population that is often misdiagnosed as other skin conditions. This study reviews an 11-year experience at a tertiary children's hospital, examining the cause, clinical and histopathological presentation, management, and treatment outcomes of pilomatrixoma. A review of the pathology database at Children's Hospital Los Angeles revealed 346 pilomatrixomas excised from 336 patients between 1991 and 2001. The hospital charts, pathology records, and plastic surgery clinic charts were reviewed with respect to variables such as sex, age at the time of presentation, clinical and histopathological presentation, preoperative diagnosis, management, recurrence, and treatment outcome. The main presenting symptom was a hard, subcutaneous, slowly growing mass. The preoperative diagnosis was accurate and consistent with the pathological diagnosis of pilomatrixoma in only 100 cases (28.9 percent). This entity should be considered with other benign or malignant conditions in the clinical differential diagnosis of solitary firm skin nodules, especially those on the head, neck, or upper limbs. The diagnosis can generally be made with a clinical examination. Imaging studies are not required unless symptoms or the location of the lesion warrants such diagnostic assessments. The treatment of choice is surgical excision, and the recurrence rate is low.

Pilomatricoma in the head and neck: CT findings in three patients

We report three cases of pilomatricoma, one in the infrahyoid neck and the others in the preauricular area. In all cases, CT showed well marginated soft tissue masses that were located mainly in the subcutaneous fat, partly attaching to the overlying skin. There was no evidence of infiltration to deeper structures. Substantial amounts of calcification were found in one tumor. Pilomatricoma should be included in diagnostic consideration when CT shows a well marginated subcutaneous soft tissue mass adherent to the skin with or without visible calcification in the head and neck region.