BACKGROUND: Pilomatricoma is a common but easily misdiagnosed tumor in children.
OBJECTIVE: To differentiate pilomatricoma from other common subcutaneous nodules in children.
METHODS: Misdiagnosed subcutaneous nodules in four children were recorded.
RESULTS: A red mass on a 7-year-old boy\'s head which had been misdiagnosed pyogenic granuloma was proved to be pilomatricoma. A red mass on an 8-month-old boy\'s face which had been misdiagnosed infantile hemangioma also turned to be pilomotricoma. A red mass on a 21-month-old girl\'s breast, which had been misdiagnosed pilomatricoma, was proved to be infantile myofibroma. A subcutaneous nodule under a 13-month-old girl\'s armpit, which had been misdiagnosed pilomatricoma, turned to be BCG-associated lymphadenitis.
CONCLUSIONS: When a child with a subcutaneous nodule attends, pilomatricoma, vascular tumors, fibrous tumors, and BCG-associated lymphadenitis should be considered.

BACKGROUND: Pathophysiology of multiple sclerosis (MS) is dominated by both inflammation and neurodegeneration. A correlation between inflammation and regulated cell death has been suggested previously. Shadow cells in the cerebrospinal fluid (CSF) are considered apoptotic cells.
OBJECTIVE: To assess the occurrence of shadow cells in MS patients in comparison to other neurological diseases (OND).
METHODS: We conducted cytological examination of CSF in 114 MS patients and 125 patients with OND, who had diagnostic lumbar puncture at the Department of Neurology, Medical University of Innsbruck, with time to laboratory processing ≤0.5 h, showed a CSF white blood cell (WBC) count ≤50/µl and a red blood cell (RBC) count ≤500/µl. Shadow cells were counted by two blinded, independent, experienced investigators, using a standardized approach on microscopic slides.
RESULTS: The number of shadow cells did not statistically significantly differ between patients with MS (median: 12, IQR: 0-85) and OND (median 6, IQR: 0-94; p = 0.106). Multivariable regression analysis including age, sex, time to laboratory processing, CSF WBC and RBC count, CSF/serum glucose ratio, CSF/serum albumin quotient and disease group as independent variables, identified WBC count as significant predictor of shadow cells (β [ln WBC count]=0.73, p<10-9), whereas the disease group had no impact (p = 0.466).
CONCLUSIONS: Occurrence of shadow cells in the CSF seems to depend on the extent of inflammatory cells rather than MS disease-specific mechanisms.

Keratin granulomas in the peritoneum are a rare finding with multiple etiologies and can be especially challenging for both the pathologist and the surgeon when these lesions are grossly visible. We report a case of a unique frozen section diagnostic scenario of evaluation of keratin granulomas in the peritoneum of a 47-year-old woman in the setting of multiple potential culprits: endometrial endometrioid adenocarcinoma following fertility sparing treatment, and a concurrent dermoid cyst. We discuss the various etiologies of keratin granulomas in the peritoneum, mechanism of their formation, diagnostic significance, as well as implications of fertility sparing treatments. To the best of our knowledge, this is the only case of keratin granulomas in the peritoneum with multiple distinct potential pathologic culprits as well the only case following fertility sparing treatment.

BACKGROUND: Pilomatricoma is a relatively common benign cutaneous adnexal neoplasm with differentiation towards the hair matrix, inner sheath of hair follicle and hair cortex. Proliferating pilomatricoma is a rare variant of pilomatricoma that can rapidly increase and may be misidentified as a malignant tumor. We herein report the cytopathological findings of proliferating pilomatricoma misdiagnosed as a malignant parotid tumor.
METHODS: A 64-year-old man noticed an acne-like nodule in the left parotid region. It was painless, but it increased to a maximum diameter of 4.5 cm over 2 years. Clinically, left parotid gland carcinoma was suspected, and fine-needle aspiration cytology was performed. Clusters of epithelial cells were observed in a necrotic background, and malignant epithelial cells derived from salivary glands were suspected. Histologically, the resected tumor was diagnosed as proliferating pilomatricoma composed of basophilic cells and shadow cells apart from the parotid gland. However, on a re-evaluation of the cytological specimens, the irregular-shaped epithelial cells were considered to be from basophilic cells. Shadow cells with nuclear disappearance were also confirmed. Tumor recurrence and metastasis have not been observed in the four years since surgery.
CONCLUSIONS: The present case was first interpreted as a malignant parotid gland tumor, but it was actually a benign skin appendage tumor. Pilomatricoma sometimes rapidly increases and may be mistaken for a malignant tumor. Although it is critical to recognize not only basophilic cells but also shadow cells, it cannot be diagnosed by cytological findings. The final diagnosis should be made on excision specimen only.

BACKGROUND: Pilomatrix carcinomas are rare, frequently occurring in older male patients. We report a case of vulvar pilomatrix carcinoma in a 30-year-old woman, the second known reported case occurring on the external genitalia.
METHODS: A 30-year-old female originally presented at an outside institution for the management of an asymptomatic vulvar mass that was biopsied and read as invasive squamous cell carcinoma. Pathology review at our institution reclassified the vulvar mass as a low-grade pilomatrix carcinoma. The patient underwent radical hemivulvectomy without an inguinal-femoral groin node dissection. She has remained without evidence of disease recurrence for more than 5 years since her diagnosis.
CONCLUSIONS: Pilomatrix carcinoma can be confused for an invasive squamous cell carcinoma. Due to its low risk of metastases, a less radical surgical approach can be taken. Consideration of this unusual malignancy is important in the determination of appropriate management.

Basal cell carcinoma with matrical differentiation is a very rare variant of basal cell carcinoma. To our knowledge, less than 30 cases have been reported. This tumor is composed of basaloid lobules showing a differentiation toward the pilar matrix cells. Recently, it has been demonstrated that beta-catenin would interfer with physiopathogenesis of matrical tumors, in particular pilomatricomas, but also basal cell carcinomas with matrical differentiation. This is a new case, with immunohistochemical and molecular analysis of beta-catenin, in order to explain its histogenesis.

Pilomatricoma (pilomatrixoma) or calcifying epithelioma of Malherbe, is a tumor with differentiation toward hair cells, particularly hair cortex cells. It frequently presents as a firm, deep-seated nodule that is covered by normal skin. Bullous pilomatricoma is an unusual clinical variant. Reports on bullous variant of pilomatricoma is sparse, and only 17 cases have been reported world-wide until date out of which only two cases are reported from India. We present a report of a 17-year-old female with a solitary reddish semi-transparent blister over her right upper arm since 3 months resembling a bouncy ball. Histopathology revealed tumor nests of basophilic cells and eosinophilic shadow cells, which are consistent with pilomatricoma.

Proliferating pilomatricoma is a proliferative variant of pilomatricoma. Although it is considered as a benign tumor, local recurrence may occur. We report a case of a 49-year-old Japanese man with 3-year history of an asymptomatic subcutaneous tumor in the nuchal area. Histological evaluation demonstrated a cystic lesion lined by a basaloid epithelium at the periphery and filled with eosinophilic cornified material containing shadow cells in upper part of the tumor, and multilobular proliferation of basaloid cells in association with small foci of shadow cells in the remaining part. Based on these findings, the diagnosis of proliferating pilomatricoma was made. No recurrence has been observed during a 3-year follow-up.