Squamous Cells in Needle Aspirates of Subcutaneous Lesions: A Diagnostic Problem

Abstract

Analysis of 1,000 cases of fine-needle aspiration biopsies of subcutaneous lesions revealed 430 cases diagnosed as malignant. Squamous cell carcinoma represented 37% of the malignant neoplasms, and many of these cases were highly differentiated tumors. Although the presence of keratinized squamous cells in superficial aspirates is strongly suggestive of squamous cell carcinoma, other lesions may produce atypical squamous cells on aspiration biopsy and should be considered in the differential diagnosis. These include acanthotic ameloblastomas, metaplastic adenocarcinomas and Warthin's tumors, branchial cleft cysts, odontogenic keratocysts, and epidermal inclusion cysts. Two-needle aspirates from these cases were incorrectly interpreted as squamous cell carcinoma. The cytologic and some of the histologic characteristics of these lesions that may pose a diagnostic problem are presented. Careful evaluation of nuclear and cytoplasmic features, cellular background, clinical findings, and history is essential to avoid a false positive diagnosis of squamous cell carcinoma.

Epithelial inclusion cyst arising in an intramammary lymph node: Case report with cytologic findings

“…In FNAs of the breast, squamous epithelium can be observed in various conditions such as metaplastic phyllodes tumor, metaplastic carcinoma, metastasis of squamous cell carcinoma, epidermoid cyst, etc. 7,8 In this case, we not only found squamous epithelium but also mature lymphocytes as a dominant component. In the other lesions mentioned above, lymphocytes are rarely present and, if present, few in number.…”

Fine Needle Aspiration Cytology and Diagnostic Pitfalls in Warthin’s Tumor with Necrotizing Granulomatous Inflammation and Facial Nerve Paralysis

“…Cytologic misinterpretation of the latter has led to false positive diagnoses of squamous or mucoepidermoid carcinoma, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] with some patients subjected to unnecessary radical surgery. 3,4,11,15,17 Other reported secondary changes observed with WT include sudden rapid growth of the mass, pain, facial nerve paralysis, fibrosis and necrotizing granulomatous inflammation. 2,8,10,16,18 The variety and frequency of these alterations are best explained by the propensity of WT to spontaneously infarct.…”

Cystic lesions of the head and neck: cytohistological correlation in 63 cases

“…[6][7][8] Dejmek and Lindholm argued that 85% of their cases with cystic masses in the H&N were correctly diagnosed by FNAC; the false-positive and falsenegative rates were 2% and 4%, respectively. 2,8,10,11 Warthin's tumour with prominent squamous metaplasia is a rather frequent source of error. 8 The two major problems in the diagnosis of the cystic masses of the H&N are the inadequacy of the aspirates from the neoplasms and the cytological atypia that may be found in benign lesions.…”