CASE REPORT

Basosquamous Cell Carcinoma of the Anus

Orestis Ioannidis & Angeliki Cheva &

George Paraskevas & Anastasios Kotronis &

Nikolaos Papadimitriou & Stavros Chatzopoulos &

Athina Konstantara & Apostolos Makrantonakis &

Antonios Sakkas & Emmanouil Kakoutis

Published online: 18 May 2012# Springer Science+Business Media, LLC 2012

Introduction

Cancer of the anus is a rare neoplasm in the general populationand accounts for only about 1.2–2 % of gastrointestinal can-cers [1–3]. Anal carcinoma usually appears in the fifth andsixth decades of life and shows a female predominance [1–3].Regarding anatomy, anal carcinomas are divided into thoseoccurring within the anal canal and those occurring at the analverge [1]. The most common malignant anal tumor is squa-mous cell carcinoma and its variants whereas other more rarelesions include adenocarcinoma, small cell carcinoma, undif-ferentiated carcinoma, melanoma, lymphoma sarcoma, and

perianal basal cell carcinoma [1–3]. Basal cell carcinoma isa very rare anal tumor of the anal margin representing only0.2 % of the anorectal tumors [1, 4] and with only a few morethan a hundred cases having been reported [5]. Clinically, thecancer presents usually as a slowly growing sharply margin-ated area with raised edges and central ulceration which canextend into the anal canal to the squamous zone [3–5]. Wepresent a very rare case of basosquamous carcinoma of theanus and emphasize this rare aggressive variant of basal cellcarcinoma and its differential diagnosis from basaloid carci-noma an aggressive variant of squamous cell carcinoma.

Case Report

A79-year-oldmale presented to our clinic complaining about alesion in the anus he has first noticed about 14 months ago.Clinical examination of the anus demonstrated an ulcer of theanal margin at the 5 o'clock position with raised borders andbluish tincture, and digital examination revealed an area ofinduration extending above the dentate line. Proctoscopyshowed a 3.5×1 cm lesion extending into the anal canalpassing the dentate line and infiltrating the rectal mucosa.The possible diagnosis of an anal cancer was made, and a widelocal elliptical surgical excision was performed under generalanesthesia. The excised specimen measured 5.5×2.5×1.5 cmand extended to the muscular layer. Histopathology revealed abasosquamous carcinoma of the anus with negative margins(Figs. 1, 2, and 3). Due to the more aggressive nature of thebasosquamous carcinoma and the increased risk of recurrenceand metastasis, the patient was submitted to extensive workupwith abdominal computed tomography, chest X-ray, and bonescanning which were all negative and intense follow-up every3 months for the first year and then every 6 months. Threeyears after the diagnosis, the patient is free of disease withoutlocal recurrence or distal metastasis.

O. Ioannidis (*) :A. Kotronis :N. Papadimitriou :S. Chatzopoulos :A. Konstantara :A. Makrantonakis :E. KakoutisFirst Surgical Department,General Regional Hospital ‘George Papanikolaou’,Thessaloniki, Greecee-mail: telonakos@hotmail.com

A. ChevaDepartment of Pathology,General Regional Hospital ‘George Papanikolaou’,Thessaloniki, Greece

G. ParaskevasDepartment of Anatomy, Medical School,Aristotle University of Thessaloniki,Thessaloniki, Greece

A. SakkasMedical School,Aristotle University of Thessaloniki,Thessaloniki, Greece

Present Address:O. IoannidisAlexandrou Mihailidi 13,54640 Thessaloniki, Greece

J Gastrointest Canc (2012) 43 (Suppl 1):S184–S186DOI 10.1007/s12029-012-9392-3

Discussion

Basal cell carcinoma represents the most common skincancer developing primarily on sun-exposed skin, usu-ally in elderly patients [4, 5]. Basal cell carcinoma canbe classified in indolent growth subsets including thesuperficial, nodular, and micronodular basal cell carci-noma and in aggressive growth variants including theinfiltrative, morpheaform (sclerosing), and basosqua-mous (metatypical) basal cell carcinoma [6]. The anusis a rare anatomic location for basal cell carcinoma,which in most cases has a solid or adenoid pattern [4, 5],while the presence of basosquamous carcinoma of the anus isextremely rare. Differential diagnosis of basosquamous carci-noma from basal cell carcinoma and from basaloid carcinomais of critical significance [3–5].

Basosquamous carcinoma is a rare aggressive variantof basal cell carcinoma accounting for 1.2–2.7 % withan increased risk of recurrence (12–51 %) and metasta-sis (5 %) compared to basal cell carcinoma [7]. Basos-quamous carcinoma was firstly described in the earlytwentieth century and has now been recognized as atype of basal cell carcinoma [7–9]. Histopathologically,basosquamous carcinoma demonstrates areas of basalcell carcinoma and squamous cell carcinoma with orwithout a transition zone [7]. Malignant basal cells withpalisading nuclei and scant basophilic cytoplasm andmalignant squamous cells with larger, polygonal cellswith abundant eosinophilic cytoplasm and larger opennuclei with prominent nucleoli are present within acollagenized, fibroblast-rich stroma [7–9]. Immunohisto-chemistry is positive for AE1 and AE3 both for basalcells and squamous cells and also positive for Ber-EP4for the basal cell component and for CAM.52 for thesquamous cell component [4, 5, 7, 8, 10, 11]. In thepresent case, the immunohistochemistry for Ber-EP4was negative.

Basaloid squamous cell carcinoma is a rare aggres-sive subtype of squamous cell carcinoma that was firstdescribed in the late twentieth century [10, 12] with apoorer prognosis and an increased risk of lymph node

involvement (40–70 %) and distant metastasis (75 %)compared to squamous cell carcinoma [11]. Histopatho-logically, basaloid carcinoma is characterized by thepresence of basaloid cells and squamous cells [12].The basaloid cells, which have an exaggerated nuclearto cytoplasmic ratio, form nests, lobules, and cribriformpatterns [10], while a definable area of squamous cellcarcinoma must be present [10, 12]. Immunohistochem-istry reveals positivity for 34βE12, epithelial membraneantigen (EMA), and focally CEA [10].

Differential diagnosis between basosquamous andbasaloid squamous cell carcinoma should be made asboth tumors can demonstrate a combination of squa-mous, basaloid, and adenoid features and can be foundin the squamous zone, and is crucial as the latter ismore aggressive than the first and, in the large majorityof cases, can be made by standard hematoxylin andeosin staining which shows more cellular and nuclearpleomorphism, less conspicuous peripheral palisading,atypical mitosis, and large eosinophilic necrotic areasin basaloid carcinoma [4, 5, 10]. However, this canbecome particularly difficult in small biopsies whereimmunohistochemistry can aid the differential diagnosis.Basosquamous carcinoma is positive for Ber-EP4 andnegative for EMA, while the basaloid carcinoma ispositive for 34βE12 and EMA [5, 10, 11]. In thecurrent case based on morphology and immunohisto-chemistry, the diagnosis of basosquamous carcinomawas made despite the negative Ber-EP4.

Fig. 1 Hematoxylin and eosinstain showing both the basaloidand squamous component(a ×100) and separately thebasaloid (b ×200) and squamous(c ×200) component

Fig. 2 The carcinoma extended both towards the perianal skin (a ×40)and towards the bowel mucosa (b ×40)

J Gastrointest Canc (2012) 43 (Suppl 1):S184–S186 S185

Local excision or radiation is sufficient treatment for analbasal cell carcinoma, and metastases are extremely rare [3, 5,13]. However, the treatment of choice for anal basosquamousand basaloid carcinoma is not yet established but should prob-ably be based on treatment options of these tumors occurring atother anatomical sites. In cases of basosquamous carcinoma,where surgical excision is probably the treatment of choice, thesurgical margins should be wider, and even then, local recur-rence is high [9]. Other treatment options include radiotherapyand Mohs micrographic surgery [9], which is related withlower recurrence rate. Furthermore, regarding the treatmentof basaloid carcinoma, a surgical excision, in this case evenabdominoperineal resection, with postoperative radiotherapyand chemotherapy is indicated [11, 13].

In conclusion, anal basosquamous carcinoma is a rareaggressive variant of basal cell carcinoma, an already rarecancer of the anus. The correct diagnosis of this variant issignificant as it requires a more wider excision and closemonitoring than basal cell carcinoma due to an increasedrecurrence rate, and its differential diagnosis from basaloidsquamous cell carcinoma is also of great significance as,compared to basaloid carcinoma, it does not present soincreased a risk for lymph node involvement and distantmetastasis and so does not require extensive surgical exci-sion and postoperative chemoradiation.

Conflict of interest The authors declare that they have no conflict ofinterest.

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Fig. 3 Immunohistochemistry was positive for CK 8/18 (CAM 5.2) (a ×200), CK 5/6 (b ×200), LMK (c ×200), p63 (d ×200), and CK 19 (e ×200)and negative for BER Ep4 (f ×200), CK 7 (g ×200), EMA (h ×200), and pCEA (i ×200)

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