About CT & MR, CT/PET, U/S
Imaging is the traditional modality for staging of most cancers. However, skin cancers in particular do not lend themselves to imaging as a form of staging in many cases, even more advanced skin cancers. Invasive cancers can be well assessed with visual examination and digital palpation for depth and extent. Imaging may still be required for evaluation of lymph node metastases.
Evaluation of local extent of skin cancers can be done with CT scans, MRI scans, and ultrasound. However, often all that these modalities show is what the clinician already knows. Imaging confirms tissue density changes due to cancer invasion that is easily palpable. Furthermore, CT and MRI is not even as sensitive as digital palpation for cutaneous induration and thickening by cancers. Therefore, CT and MRIs are used primarily for evaluation of deeper structures that are nonpalpable. CT and MRI could be used to delineate the extent of a deeply invasive cancer and its relation to the large blood vessels such as jugular vein and carotid artery.
Common areas of head and neck that require evaluation for local extent of the cancer include the orbit and the infratemporal fossa. Both are best evaluated with an MRI. Evaluation of a deep tumor spread behind the mandible within the parotid is also useful with an MRI. This may determine that the cancer is spreading much deeper in the parotid gland and facial nerve may be at risk. CT scan with contrast can visualize almost everything that MRI can, but with less resolution. CT scan excels at evaluating relationship of soft tissue tumors to bone. It can determine if there is bone erosion. MRIs are uniquely capable of evaluating tumor spread within fatty tissues. Fatty tissues have unique signal on the MRI (high on T1).
Evaluation of the regional metastasis such as lymph node metastasis of tumors often requires imaging. Both CT and MRI are adequately useful in this. An underutilized modality is ultrasound. Despite its low cost, it has been shown to be just as accurate in detecting cervical lymph node metastasis as CT and MRI at a much lower expense and without the need for IV contrast.
CT/PET scan is a unique modality for determining location of cancers anywhere in the body. The PET scan component is able to find hypermetabolic foci that could be diagnostic for cancer metastasis. The limitation is the 4 mm diameter size of the lesion necessary to provide high enough signal for detection. Therefore, micrometastases are nondetectable with a CT/PET scan. CT/PET scan can detect small lymphatic metastases with greater accuracies than CT or MRI alone.
Smoothened and Patched and Sonic Hedgehogs – From Cyclopic Sheep to Targeted Basal Cell Carcinoma Treatment
What does Frizzled, Frazzled, Dishevelled, and Smoothened have to do with the Sonic Hedgehog? These are some of the humorously named genes in Drosophila fruit flies that also happened to be expressed in humans. Besides adding character to the genes, these names occasionally reflect the traits they describe. Hedgehog (Hh) gene is part of the…Read More
Does medical economics bias the community standards for treatment of skin cancers? If the answer is yes, then photodynamic therapy serves as an illustrative example of this bias. Private practice dermatology in the US and National Health Service of UK are practice settings with significantly different economics and also different treatment goals. The one’s is…Read More
HISTORY 71-year-old woman presents with a nasal tip lesion biopsied on 6/12/2017 showing basal cell carcinoma, superficial and micronodular type. There is a history of treatment with topical chemotherapy and Mohs excision of other sites. Patient is anxious about the possible extent of nasal carcinoma and the reconstruction required. DISCUSSION This case presents an excellent…Read More
HISTORY 104 year old man presented in 2/2017 with basal cell carcinoma of the left frontal scalp and basosquamous carcinoma of the left eyebrow. On 3/21/2017 the patient underwent a wide local excision and Mohs margin excision of orbit and forehead. At the time he also had Mohs excision of the scalp forehead basal cell…Read More
HISTORY 79 year old woman presented with a 3 month history of right angle of jaw mass hardening over time. A biopsy of a separate lesion of the right central cheek on 2/21/17 showed papillated Bowen’s Disease. The jaw mass was biopsied on 2/24/17 and revealed invasive Bowen’s carcinoma – squamous cell carcinoma. DISCUSSION This…Read More
HISTORY 70-year-old man with history of sarcoidosis on chronic prednisone. Left preauricular cheek squamous cell carcinoma was treated with Mohs excision and inferior SMAS partial island flap reconstruction. The healing was complicated by wound dehiscence, partially due to wound ischemia and wound tension. DISCUSSION The third case represents a dehiscence due to likely ischemia…Read More
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