Cytopathological findings of proliferating pilomatricoma misdiagnosed as a malignant parotid gland tumor.

Diagn Pathol 2018 Aug 28;13(1):65. Epub 2018 Aug 28.

Department of Pathology and Laboratory Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan.

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.

Case Presentation: 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.

Conclusion: 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.

Download full-text PDF

Source
https://diagnosticpathology.biomedcentral.com/articles/10.11
Publisher Site
http://dx.doi.org/10.1186/s13000-018-0738-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6114043PMC
August 2018
47 Reads

Publication Analysis

Top Keywords

proliferating pilomatricoma
16
parotid gland
16
cells shadow
12
basophilic cells
12
shadow cells
12
malignant parotid
12
epithelial cells
12
cells
9
left parotid
8
malignant tumor
8
gland tumor
8
pilomatricoma rapidly
8
cytopathological findings
8
pilomatricoma misdiagnosed
8
findings proliferating
8
misdiagnosed malignant
8
pilomatricoma
7
tumor
7
malignant
6
parotid
6

References

(Supplied by CrossRef)

PE LeBoit et al.
2006

S Kaddu et al.
J Cutan Pathol 1997

LB Lemos et al.
Ann Diagn Pathol 2004

S Singh et al.
Cytopathology 2007

S Sivakumar et al.
Acta Cytol 2007

D Sharma et al.
J Clin Diagn Res 2014

S Bellafiore et al.
Diagn Cytopathol 2016

S Kaddu et al.
Am J Dermatopathol 1996

Similar Publications