Spiradenoma
Spiradenoma (also called eccrine spiradenoma) is a benign cutaneous adnexal tumor arising from epithelial stem cells that differentiate toward the secretory or ductal part of the sweat gland. Clinically it is known for being exquisitely tender even to a light touch (a classic painful cutaneous tumor) and for its solid, lobulated structure lying deep in the dermis or subcutis.
ALPK1 and CYLD Mutations and the Mechanism of Pain
- ALPK1 (alpha-kinase 1) mutation: recent molecular studies have found a gain-of-function point mutation in ALPK1 in most solitary spiradenomas. ALPK1 keeps the NF-κB signaling pathway permanently switched on, driving proliferation of the glandular epithelium and stimulating production of nerve growth factor (NGF).
- CYLD mutation: like cylindroma, spiradenoma can occur as part of the inherited Brooke-Spiegler syndrome (BSS), caused by mutations in the CYLD tumor suppressor gene (16q12.1). When spiradenoma and cylindroma appear in the same lesion, the result is a hybrid tumor called spiradenocylindroma.
- Why it hurts: the sudden, sharp tenderness of spiradenoma comes from three factors working together:
- A dense network of unmyelinated sensory C fibers branching through the tumor stroma.
- Local contraction of myoepithelial cells, which raises the pressure inside the nodule.
- Build-up of pain mediators such as substance P, bradykinin and histamine.
Malignant Transformation (Spiradenocarcinoma)
Although benign, a spiradenoma that has been present for many years can undergo secondary malignant change into spiradenocarcinoma.
- Additional mutations in TP53 or PIK3CA, or beta-catenin rearrangement, cause the tumor to lose its biphasic pattern, with a sharp rise in proliferation (Ki-67 > 30%), invasion through the capsule, and a risk of regional lymph node and distant metastasis (30–40%).
Because spiradenoma lies deep in the dermis and is closely tied to sensory nerve branches, our approach at Haute-Derma involves:
- Neurovascular imaging: high-frequency skin ultrasound with spectral Doppler to map the feeding vessels and the depth of the tumor base.
- Cosmetic en bloc microsurgical excision or Mohs surgery: removing the whole tumor together with its fine fibrous capsule without cutting the main nerve branches, which relieves the pain and lowers the risk of recurrence.
Histopathology, Immunohistochemistry (IHC) and Imaging Criteria
Characteristic Microscopic Picture
Under the light microscope, spiradenoma appears as one or more large, round, deeply staining basophilic "blue" nodules in the deep dermis or subcutis:
- Biphasic cell population:
- Peripheral cells: small, with dark nuclei and scant cytoplasm, lined up in a palisade at the edge of the tumor nests (basaloid germinative cells).
- Central cells: larger, with pale nuclei and more cytoplasm, arranged around small duct-like lumens containing secretions.
- Interspersed T lymphocytes: small lymphocytes scattered within the tumor lobules themselves. This is a key histologic feature that separates spiradenoma from basal cell carcinoma (BCC).
- Stromal hyaline material: pink, PAS-positive hyaline bands surround the lobules or collect as small droplets within them.
Differential Immunohistochemistry (IHC) Panel
| IHC marker / stain | Where it is expressed | Diagnostic significance |
|---|---|---|
| p63 / CK5/6 | Small peripheral cells of the lobules | Strongly positive (++), confirming basaloid germinative cells |
| CK7 / CEA / EMA | Central cells and small duct lumens | Clearly positive along ducts (+), confirming sweat gland differentiation |
| CD3 / CD8 | Lymphocytes scattered within the tumor | Positive T lymphocytes (+), a key distinguishing criterion |
| S100 / PGP9.5 | Fine sensory nerve fibers around the tumor | Positive (+), explaining the tenderness |
| PAS + diastase | Basement membrane around lobules and hyaline droplets | Positive (+), showing hyaline matrix |
| Ki-67 | All tumor cells | <5% in benign tumors; >30% with transformation to spiradenocarcinoma |
High-Frequency Ultrasound and Dermoscopy Criteria
- High-frequency skin ultrasound:
- Structure: a round or oval hypoechoic mass with clear lobulation, located in the deep dermis or subcutis.
- Capsule and enhancement: very sharp borders, a thin echogenic capsule and posterior acoustic enhancement.
- Color Doppler: marked internal blood flow (hypervascularity), which explains the swelling and pain on contact.
- Dermoscopy:
- Background: structureless pink-red, blue-gray or pale violet areas.
- Vessels: arborizing-like vessels or linear vessels around the tumor.
- Hazy structures: white or pale yellow cloud-like dots corresponding to areas of hyaline change.
Clinical Features
- Typical lesion: a solitary firm subcutaneous nodule, 0.5–2 cm across, pink-red, pale violet or skin-colored.
- Classic symptom: intense tenderness with light pressure or temperature change, or pain that comes on by itself. The pain may radiate along a nearby nerve.
- Common sites: head, face, neck and upper trunk.
Our Treatment Protocol at Haute-Derma
At Haute-Derma, managing spiradenoma has two core goals: resolve the pain by removing the tumor completely at its root, and preserve nerve function and the appearance of the skin as much as possible.
Deep Assessment and Rapid Histologic Confirmation
- High-frequency skin ultrasound: pinpoints how deep the lower edge of the tumor lies relative to the deep fascia, and maps the feeding vessels so bleeding can be controlled during surgery.
- Biopsy with IHC to screen for malignancy: staining for p63, CK7, CD3 and the Ki-67 index confirms a benign biphasic pattern and rules out transformation to spiradenocarcinoma.
Tailored Microsurgical Excision
En bloc microsurgical excision (full-thickness excisional microsurgery):
- Used for typical benign spiradenomas.
- The incision follows the natural skin tension lines (Langer's lines). The tumor is carefully dissected along its fine fibrous capsule, and the feeding microvessels and infiltrating sensory nerve twigs are divided without rupturing the lobules.
Mohs surgery (Mohs micrographic surgery):
- Used for tumors on the face, ears or neck, for recurrent tumors, or when IHC raises suspicion of malignancy (Ki-67 > 10%).
- The entire lateral and deep margin is checked on frozen sections during surgery, and we stop only once the margins are confirmed microscopically clear of tumor cells.
Nerve Decompression, Biological Repair and Cosmetic Closure
- Irrigating the cavity with exosomes + PDRN: right after the tumor is removed, the defect is coated with a stem cell exosome solution combined with PDRN to soothe the injured nerve endings straight away, help prevent postoperative nerve pain and speed healing.
- Three-layer buried subcuticular closure (multilayer subcuticular closure): the defect is closed with ultra-fine 7/0 cosmetic sutures, keeping tension on the skin surface to a minimum.
- Vbeam 595 nm laser: performed after 7–10 days to reduce the new blood vessels around the incision, so the scar settles flat and smooth and blends better with the surrounding skin.
