We report a 58-year-old woman with cutaneous adenoid cystic carcinoma arising on the chest treated with Mohs micrographic surgery. The patient remained tumor-free at 24-month follow-up. To date, only six other cases of cutaneous adenoid cystic carcinoma were reportedly managed by Mohs surgery. Cutaneous adenoid cystic carcinoma has low potential for distant metastasis but is notorious for its aggressive infiltrative growth pattern, frequent perineural invasion, and high risk of local recurrence after excision. We propose that Mohs surgery is an ideal method to achieve margin-free removal of cutaneous adenoid cystic carcinoma. A brief literature review is provided.
Adenoid cystic carcinoma (ACC) is commonly known as a malignant neoplasm of salivary glands in the head and neck region [
A 58-year-old, otherwise healthy, Caucasian female was referred to the Department of Dermatology at the University of Wisconsin for treatment of a biopsy proven adenoid cystic carcinoma on the right mid-chest. She had a lesion of “basal cell carcinoma” surgically excised on her right mid-chest 14 years previously. The actual slides of the previous excision were not retrievable, while the pathology report did state that the lesion was “a basal cell carcinoma which in some areas presents gland-like formations, adenoid cystic characteristics and focal areas of keratinization, but it predominantly is an adenoid basal cell carcinoma.” The patient had done well until one year prior to the referral when she noted two tender, flesh-colored nodules adjacent to the scar. A punch skin biopsy confirmed the diagnosis of adenoid cystic carcinoma concerning for its infiltrative growth pattern and perineural invasion.
A thorough preoperation physical examination revealed a healthy-appearing Caucasian female with an approximately 15 × 15 mm, poorly defined, tender, erythematous patch with focal crust and a hypopigmented scar notable on the right mid-sternum region (Figure
Clinical morphology prior to the Mohs surgery for a biopsy-proven ACC: A 58-year-old woman with a poorly defined erythematous patch on the mid-chest, measuring about 15 mm approximately. Note focal crust and a hypopigmented scar within the patch. An adenoid BCC of the right chest was treated by excision 14 years earlier. ACC: adenoid cystic carcinoma, BCC: basal cell carcinoma.
The patient underwent Mohs surgery for excision of the tumor. The specimens were processed using fresh frozen tissue stained with hematoxylin and eosin. It revealed an infiltrative dermal tumor composed of basaloid cells arranged in cords, nodules, and cribriform islands embedded in a fibrous stroma, with a lack of continuity with the surface epidermis. Prominent glandular and ductal differentiation and cystic spaces containing mucinous materials, and eosinophilic globules of amorphous material were noted (Figure
Microscopic finding of typical ACC characterized by multiple glandular and ductal structures in the deep dermis. There are multiple cysts with some being clear and others with eosinophilic materials (Fresh frozen tissue, H & E, original magnification ×40). ACC: adenoid cystic carcinoma.
High magnification demonstrating characteristic cribriform pattern in which multiple cysts are embedded in an island of basaloid cells. Three representative cysts are shown by arrows (Fresh frozen tissue, H & E, original magnification ×100).
The cyst lining showing cytoplasmic blebbing reminiscent of apocrine-like decapitation secretion within the cyst (Fresh frozen tissue, H & E, original magnification ×400).
Several foci of ACC are situated adjacent to nerves (n) as indicated by arrows (Paraffin-embedded tissue, H & E, original magnification ×200). ACC: adenoid cystic carcinoma.
To further rule out an extracutaneous primary site of the tumor and search for evidence of metastasis, additional work-up was completed including a breast examination, mammogram, computed tomographic (CT) scans of the head, neck, chest, and abdomen, and head and neck examination by an otolaryngologist. All were within normal limits. The patient is now 24 months postoperative, and there is no sign of local recurrence or distant metastasis.
The authors acknowledge that for our patient, the Mohs excision of the tumor preceded the work-up for possible extracutaneous sources. The work-up was slightly delayed due to prior-authorization processes involved with her insurance company. We wish to emphasize that ideally it is advisable to complete the entire work-up prior to excision, in order to exclude any extracutaneous source and thus confirm the diagnosis of primary cutaneous ACC.
ACC is most commonly seen as a neoplasm of the major and minor salivary glands. It can also arise from a variety of primary sites, including the external auditory canal, lacrimal gland, respiratory tract, uterus, cervix, vulva, breast, thymus, prostate, esophagus, and skin [
Cutaneous ACC was first reported by Boggio in 1975 [
Microscopic findings of cutaneous ACC are characterized by basaloid cells in the mid to deep dermis, arranged in cords and islands forming tubular structures and cribriform patterns, usually with a lack of connection to the overlying epidermis or adnexal structures [
Whether cutaneous ACC is a tumor of eccrine or apocrine origin has not been determined. There is some observational evidence suggesting that this tumor might be apocrine in origin. ACC often arises from ceruminous glands of the external ear canal, which are modified apocrine glands.
Histologically, cutaneous ACC must be differentiated from adenoid basal cell carcinoma (BCC). Adenoid BCC also may demonstrate a cribriform pattern with areas of cystic degeneration and abundant mucin. However, it can be differentiated from cutaneous ACC by its continuity with the epidermis or adjacent hair follicle, the presence of peripheral palisading and retraction artifact, and often the lack of perineural invasion. Immunohistochemical studies may assist in further differentiating adenoid BCC from ACC. For instance, in contrast to adenoid BCC, cutaneous ACC often stains positively for S-100, epithelial membrane antigen (EMA) and is variably positive with carcinoembryonic antigen (CEA) [
Another close mimicker of cutaneous ACC is mucinous carcinoma of the skin which typically shows islands of basaloid eccrine cells embedded in lakes or pools of mucin separated by fibrous septa [
Histological differential diagnosis of ACC should also include primary cutaneous cribriform apocrine carcinoma, which is a rare, low-grade cutaneous apocrine carcinoma. Microscopically primary cutaneous cribriform apocrine carcinoma is a nonencapsulated dermal tumor with an extensive cribriform pattern formed by multiple interconnected basophilic epithelial cells that are arranged in solid nests or tubular structures, and many small round spaces in between [
The standard treatment for cutaneous ACC is wide local excision with tumor-free margins established by permanent sections [
Only 7 cases [
Cases of primary cutaneous adenoid cystic carcinoma treated with mohs micrographic surgery.
Ref. | Sex/age | Duration | Presentation | Location | Tissue processed | PNI | LN | Adjuvant therapy | F/U (m) |
---|---|---|---|---|---|---|---|---|---|
[ | F/68 | Sx for ACC 5 yrs ago | Lump in a scar | Back | Permanent | (−) | (−) | None | 18 |
[ | M/65 | 1 yr | Lump | Scalp | Fresh frozen | (−) | (−) | None | 10 |
[ | F/45 | Sx for ACC 2 & 7 yrs ago | Tender scar | Scalp | Fresh frozen | (−) | (−) | None | 18 |
[ | F/57 | 1 yr | Nodule | Scalp | Fresh frozen | (−) | (−) | Local rad | 28 |
[ | F/62 | Months | Painless nodule | Scalp | NS | (+) | (−) | None | 6 |
[ | M/59 | 1 yr | Asymptomatic nodule | Eyelid | NS | (+) | (−) | None | 12 |
Our case | F/58 | Sx for BCC 14 yrs ago | Tender nodules in a scar | Chest | Fresh frozen and permanent | (+) | (−) | None | 24 |
AAC: adenoid cystic carcinoma; BCC: basal cell carcinoma; F: female; F/U: follow-up; LN: lymph node; M: male; m: months; NS: not stated; PNI: perineural invasion; rad: radiation; Ref: reference; Sx: surgery; yrs: years;
It is worth clarifying the term “discontinuous perineural extension.” While tumors normally spread in a continuous manner, they may spread asymmetrically along the nerve. Also, tissue manipulation for horizontal sections during Mohs surgery may distort a nerve and result in “skip-areas" [
Some authors have questioned whether routine hematoxylin and eosin staining of fresh frozen sections from Mohs surgery provides optimal visualization of tumor margins in the treatment of cutaneous ACC. Lang et al
Based on the nature of cutaneous ACC and the success rate of Mohs surgery in other cutaneous malignancies that exhibit perineural invasion, we propose that Mohs surgery is superior to wide local excision to achieve a more complete excision of this tumor and to reduce the rate of local recurrence. In the seven cases treated by Mohs surgery, there has been no local recurrence with a follow-up range of 10–28 months. However, a limited case number and insufficient follow-up period does not allow us to draw a definitive conclusion. We hope to see more cases managed by Mohs surgery, so that one might be able to compare whether there is indeed a lower recurrence rate in cases treated with Mohs surgery as opposed to wide local excision. Additionally, since recurrence of cutaneous ACC can occur as late as 35 years postexcision [