Basosquamous Cell Carcinoma
What is basosquamous carcinoma?
Meta-typical carcinoma (MTC) or basosquamous carcinoma is a remarkable malignancy with features of both basal and squamous cell carcinoma. It is typically located on the back and face, often with clinical features of basal cell carcinoma but tending to be more aggressive with enhanced prospects of lymph node or distant metastases.
"Significant factors predictive of recurrence (P<0.01) were male gender, positive surgical resection margin, lymphatic invasion, and perineural invasion. Although tumor size was not a statistically significant factor overall (P = 0.076), the 3 patients with lymph node metastases had large tumors (measuring 2 cm, 5 cm, and 5 cm, respectively)."
"These types are associated with poor outcome in cases of incomplete surgical removal... BCC is the most common cancer in Caucasians . The hallmark of treatment remains surgery with wide excision, despite the fact that non-surgical options including radiotherapy, topical immune modulators, photodynamic therapy, and systemic hedgehog inhibitors also belong to the current armamentarium of BCC therapy... In facial BCC or relapsing BCC, Mohs technique is preferable due to the lower rate of recurrences compared with wide excision and the tissue sparing effect... Cryotherapy is no longer recommended for the treatment of NMSCs such as SCC and BCC . Unsuccessful laser treatment has also been documented in this setting . The aggressiveness of MTBCC warrants wider margins compared with the surgical treatment of conventional BCC in case Mohs surgery is unavailable . Standard recommendations include a surgical margin of 3 mm for the face and 5 mm for other sites . If there is a history of rapid tumour growth, wider margins may be desirable (5 mm for the head/neck and 10 mm for other areas) . Mohs micrographic surgery is the safest treatment approach, but it is more expensive. It is the best choice for high-risk locations such as the ears, mid-face, recurrent or large tumours ...
MTBCC is more proliferative, with a mitotic activity that is eight times greater that of the normal epidermis, compared with BCC in which it is only four times greater. In addition, MTBCC also shows a more frequent presence of atypical mitotic figures, such as multipolar or tripolar mitoses . Our patients fulfilled the criteria for a high-risk BCC, i.e. metatypical histology, perineural infiltration, infiltration of muscles and galea aponeurotica and relapse . In such cases complete excision can be a challenge . Relapses are not uncommon demanding for a follow-up of such patients. This has been illustrated by a large randomized trial from the Netherlands . Here, the recurrence rate of relapsed BCC was 12.1% with wide excision versus 2.4% with Mohs technique . We performed delayed Mohs in our department and achieved an R0 resection. Combined flaps and transplants are useful to cover most large scalp defects after skin tumour removal even when bone is exposed. Using a rose drill small holes can be created in the tabula externa of the calvaria which support a better nutrition of skin grafts [26–28]. Other options for delayed defect closuring include external and internal tissue expanders [29, 30]. Sometimes a delayed loss of transplants can be observed. In case of exposed calvaria, as in the present patient, a sandwich technique with engineered dermal template and skin grafts in the same session is a useful tool to cover exposed bone, cartilage or tendons to ensure graft taking . Although in most cases split-skin mesh grafts are used, its application with full thickness skin grafts is also successful .
Using this technique we obtained a stable wound healing after complete removal of a relapsing MTBCC. In more advanced MTBCC cases an interdisciplinary approach is helpful .