Indian Journal of Pathology and Microbiology

LETTER TO EDITOR
Year
: 2014  |  Volume : 57  |  Issue : 2  |  Page : 345--347

Basaloid carcinoma: Rare human papillomavirus-related variant of squamous cell carcinoma of the anorectum: A case report


Rajib Kumar Gupta1, Raghavendra Pillappa1, Ilya Stone2, Nadeem Zafar3,  
1 Departments of Pathology and Laboratory Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
2 Memphis VA Medical Center, Memphis, TN 38104, USA
3 Departments of Pathology and Laboratory Medicine, University of Tennessee Health Science Center, Memphis, TN 38163; Memphis VA Medical Center, Memphis, TN 38104, USA

Correspondence Address:
Rajib Kumar Gupta
MD, Department of Pathology and Laboratory Medicine, University of Tennessee Health Science Center, 930 Madison Ave, 5th Floor, Memphis, TN 38163
USA




How to cite this article:
Gupta RK, Pillappa R, Stone I, Zafar N. Basaloid carcinoma: Rare human papillomavirus-related variant of squamous cell carcinoma of the anorectum: A case report.Indian J Pathol Microbiol 2014;57:345-347


How to cite this URL:
Gupta RK, Pillappa R, Stone I, Zafar N. Basaloid carcinoma: Rare human papillomavirus-related variant of squamous cell carcinoma of the anorectum: A case report. Indian J Pathol Microbiol [serial online] 2014 [cited 2020 May 31 ];57:345-347
Available from: http://www.ijpmonline.org/text.asp?2014/57/2/345/134747


Full Text

Sir,

Basaloid carcinoma or basaloid squamous cell carcinoma (BSCC) is a rare variant of squamous cell carcinoma (SCC) occurring in the anorectal region. Clinically and endoscopically, the tumor often mimics a rectal adenocarcinoma although the etiopathogenesis and histopathology of the two are quite distinct. BSCC usually arises from the dentate line and straddles both the lower rectum and the upper anal canal. Here, we report a case of basaloid carcinoma occurring at the anorectal junction in a 53-year-old male which was clinically and endoscopically assumed to be rectal adenocarcinoma.

Our patient, a 53-year old diabetic and hypertensive African American male, presented at the outpatient clinic with a 3-month history of increasingly painful bowel movements and intermittent hematochezia. He did not give any history of recent weight loss or progressive constipation, and also denied any addiction for nicotine or alcohol. On testing, his HIV status was negative. There was no family history of malignancy. Systemic examination of the patient was unremarkable. Digital rectal examination revealed no hemorrhoids. An abdominal computed tomography (CT) was nondiagnostic. Positron emission tomography-CT (PET-CT) showed a focal area of abnormal metabolic activity centered in the lower rectum and anus. At colonoscopy, a large, ulcerated apple-core stricturing mass was seen at the anorectal junction [Figure 1]. A clinical diagnosis of rectal adenocarcinoma was rendered and multiple biopsies were taken. Histology confirmed a carcinoma composed of multiple islands of densely packed atypical hyperchromatic basaloid cells with characteristic peripheral palisading, embedded in a desmoplastic stroma [Figure 2]a and 2b]. The tumor cells showed scattered pyknotic nuclear debris and frequent mitoses. p63 immunostaining confirmed squamous cell origin of the tumor and the surrogate p16 stain for HPV was strongly positive [Figure 2]c and 2d]. The tumor was negative for Bcl2, synaptophysin, chromogranin and CD56 and weakly positive (membranous) for Ber-EP4 thus ruling out both neuroendocrine carcinoma and basal cell carcinoma [Figure 2]e and 2f]. A diagnosis of BSCC of the anorectum was hence given and the patient was subsequently treated with standard chemo-radiation.{Figure 1}{Figure 2}

Grinvalsky and Helwig were the first to histologically describe basaloid carcinoma or BSCC in 1956. [1] This rare SCC variant was previously also known as cloacogenic carcinoma as it is thought to arise from the transitional or cloacogenic epithelium of the dentate line which separates the anal nonkeratinizing squamous epithelium below from the rectal colonic mucosa above. [2] The differential diagnoses of this tumor in the anorectal region include rectal adenocarcinoma, neuroendocrine carcinoma, anal basal cell carcinoma and conventional keratinizing SCC of the anus. However the distinctive morphology of BSCC along with helpful immunohistochemistry can aid in its correct diagnosis. [2],[3],[4] Basal cell carcinoma, the closest mimic of BSCC is usually positive for bcl2 and Ber-EP4 while the latter is traditionally considered negative for both although a recent study has shown that Ber-EP4 can show membrane-positivity in 82% of BSCC cases thus corroborating our own findings. [5] Neuroendocrine carcinoma was easily ruled out as none of the neuroendocrine markers was positive. High-risk sexual practices and smoking are known risk factors for all variants of anorectal carcinomas, although neither was reported in our patient. This may relate to a historical fact not being volunteered by the patient. Studies have also shown a strong association of BSCC with high-risk HPV subtypes 16 and 18 (thus explaining its strong p16 positivity), compared with other variants of SCC. [6] Although WHO now recommends only the generic term of "SCCs" for all variants of anorectal SCCs, many pathologists mention this variant in their reports because of its unique morphology and more frequent association with HPV.

 ACKNOWLEDGMENT



The authors would like to thank Paul Bierman, MD, Consultant Gastroenterologist, Gastrointestinal Specialists, PC, Memphis, TN for the colonoscopy images.

References

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