A tender Growing Lesion on Trunk of a Middle-Aged Woman

Case Presentation

A healthy 35-year-old woman presented with a tender, growing lesion on her trunk since 2 years ago starting with a sterile pustule that rapidly became painful with violaceous tender borders [Figure 1]. The patient has no history of any underlying medical disease or similar ulcers elsewhere. Skin biopsy was done and histological examination revealed infiltrative tumour with islands and cords of epithelioid cells with vesicular nuclei and prominent nucleoli in which the excision of the lesion was advised [Figure 2].

Figure 1.

Tender growing lesion with violaceous borders

Figure 2.

(a) Infiltrative tumour with islands and cords of epithelioid cells with vesicular nuclei and prominent nucleoli (haemoglobin and eosin [H&E] ×40). (b) Infiltrative tumour with islands and cords of epithelioid cells with vesicular nuclei and prominent nucleoli (H&E ×200). (c) Infiltrative tumour with islands and cords of epithelioid cells with vesicular nuclei and prominent nucleoli (H&E × 400)

Question

What is the diagnosis?

Diagnosis

Basosquamous cell carcinoma.

Discussion

Basosquamous carcinoma (BSC) is a rare epithelial neoplasm with aggressive behaviours featuring both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) characteristics and histopathology.[1] Based on the World Health Organization classification of tumours, BSC is described as a BCC with associated SCC differentiation.[2] BSC has reported having an incidence of 1.2% to 2.7% among all skin cancers.[1] Furthermore, BSC commonly arises from the sun-exposed area such as neck and head and rarely on extremities and trunk with predominant occurrence in older males that lasts for few years especially in the seventh decade.[1,3]

Histopathologically, BSC is defined as a tumour that contains areas of both SCC and BCC with a transitional zone. This transitional zone represents the area of lineage differentiation between the 2 continents. Classical features of BSC include basaloid cell inflammatory islands with palisade nuclei at the periphery. Cells usually form a cluster with a focal aggregation of squamous cells either distributed throughout the lesion or near the centre.[3] BSC has an aggressive local growth pattern and also the risk of metastasis that ranges from 5% to 8.4%.[1] Although the diagnosis is based on skin biopsy, incorrect diagnosis is common due to superficial biopsy. In this case, superficial layers may only present with features of BCC, while deeper layers contain BSC features.

It is believed that BSC may be missed diagnosed with other lesions such as pyoderma gangrenosum (PG) due to its clinical features. PG is a chronic inflammatory skin disease that occurs with nodules or pustules and progressively turns into a painful cutaneous ulcer with tender borders as same as our case. Although both may have similar clinical characteristics, PG is commonly associated with systematic diseases such as Crohn's disease, ulcerative colitis, and lymphoproliferative disorders in more than half of the cases.[4] PG can occur at any age but it is most commonly occurring in the second to fifth decades of life, whereas BSC generally occurs in seventh decade of life. Moreover, in adults, PG can affect any part of the body but frequently involves lower extremities, while BSC is mostly seen in head and neck area and rarely on extremities. Despite the fact, the diagnosis of PG is clinical; some criteria can help in confirming the diagnosis such as the rapid progression of ulcers and rule out of other causes of cutaneous ulcerations. PG treatment is a combination of local wound care and systemic therapy. The important point in the evaluation of PG is excluding infection and malignancy in our initial workups. As said before, PG has many differential diagnoses and can be mistaken by other conditions. Actual diagnosis can be one of the following: Malignancies, infections, manifestations of autoimmune diseases or connective tissue disorders, vascular diseases, vasculitis, and drug-induced tissue injury.[5]

No specific treatment has yet been identified as the gold standard for BSC. Various treatments are used such as Mohs micrographic surgery, excision, surgery with adjuvant radiation, laser ablation, cryotherapy, radiotherapy, chemotherapy, and smoothened inhibitors. Moreover, due to the high risk of recurrence and metastasis, close follow-up is indicated in diagnosed cases. Experts use a variety of methods to monitor their patients, including clinical and radiological monitoring.[1]

Learning points

1. BSC is a rare and aggressive epithelial neoplasm with risk of local recurrence and distant metastases, which mostly occur in sup-exposed areas such as head and neck, but rarely extremities and trunk.

2. Misdiagnosis of BSC is common due to its various clinical presentations and histopathological features. Clinicians should bear in mind that prompt diagnosis and excision of the tumour can be lifesaving.

3. BSC might be misdiagnosed as PG due to its progressive growth and tenderness on examination.

4. BSC in characterized by infiltrative tumour with islands and cords of epithelioid cells with vesicular nuclei and prominent nucleoli histopathologically.

Ethics committee/Institutional review board's permission

We also declare that the study was assessed and approved by the Institutional Ethics Committee of Shiraz University of Medical Sciences Review Board and that the letter of approval is available with us for examination.

Ethical statement

The present study was approved by the Medical Ethics Committee of Shiraz University of Medical Sciences.

Declaration of patient consent

Written Informed consent was obtained from the patient's parents to write and publish her case as a report with accompanying images.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.