Primary cutaneous mucinous carcinoma

Primary mucinous carcinoma of skin (PMCS); colloid carcinoma of skin

Primary cutaneous mucinous carcinoma is a rare low-grade adnexal carcinoma with eccrine differentiation, characterised histologically by clusters of tumour cells "floating" in pools of extracellular mucin. It typically presents on the face — particularly the eyelid, scalp and cheek — of older adults as a slowly enlarging, gelatinous, blue-grey or skin-coloured nodule. The single most important diagnostic step is to exclude metastatic mucinous adenocarcinoma from the breast, gastrointestinal tract or other primary, since the histology can be indistinguishable. Once a primary cutaneous origin is confirmed, the prognosis is excellent and Mohs micrographic surgery is the treatment of choice.

CurrentLast reviewed 26 April 2026

Clinical features

Slow-growing, gelatinous-feeling, blue-grey, translucent or skin-coloured nodule.
Most common on the face (eyelid in particular ~40%), scalp, neck and trunk.
Median age 60–70; M>F (slight).
Often present for years; may be cystic on palpation.
Differential: epidermal cyst, BCC, Merkel cell carcinoma, hidradenoma.

Histology & rule out metastasis

Nests, cords or sheets of monomorphic epithelial cells suspended in pools of basophilic extracellular mucin, divided by delicate fibrous septae.
Tubular and cribriform architecture often present.
Low-grade nuclei; mitoses uncommon.
Immunohistochemistry — primary cutaneous: CK7+, CK20−, ER+, PR+, GCDFP-15+, p63+ (myoepithelial component at periphery).
Critical step: exclude metastatic mucinous carcinoma:
- Breast — same IHC profile; clinical examination, mammography and breast ultrasound mandatory.
- Colorectal — CK20+, CDX2+, CK7−.
- Lung, pancreas, ovary, prostate.
The presence of an in-situ component or focal apocrine differentiation favours primary cutaneous origin.

Staging workup

Detailed history (any prior cancer, breast lump, change in bowel habit, weight loss, etc.).
Full skin examination including breast and oral mucosa.
Mammography (women) and breast ultrasound; consider in men with suspicious lesions.
CT chest/abdomen/pelvis to exclude an internal primary, especially for tumours not on the face.
Discuss at skin cancer MDT (and breast MDT if eyelid lesion in a woman).

Management

Mohs micrographic surgery is the treatment of choice — preserves cosmesis (frequently periorbital) and minimises recurrence.
Wide local excision with 1 cm margins is acceptable where Mohs is unavailable.
Sentinel lymph node biopsy not routinely indicated; nodal metastasis rare.
Adjuvant radiotherapy reserved for incomplete margins or recurrent disease.
Hormone-receptor-directed therapy may be considered for the rare metastatic case (off-licence).

Prognosis

Excellent — local recurrence after Mohs <10%; metastasis <5%. The principal long-term concern is misdiagnosis as benign or as metastatic carcinoma at presentation. Standard skin-cancer follow-up (annual for 5 years) is appropriate after complete excision.