Introduction
Hidradenitis suppurativa (HS) is a chronic, debilitating, inflammatory skin condition
characterized by recurrent painful nodules, cysts, and abscesses that can rupture
and lead to the formation of sinus tracts and scarring. In 2015, the tumor necrosis
factor-α (TNF-α) inhibitor, adalimumab, was approved for the treatment of moderate-to-severe
HS.
1
TNF-α inhibitors may increase the risk of nonmelanoma skin cancers, particularly squamous
cell carcinoma (SCC).
2
Patients with HS are 4.6 times more likely to go on to have nonmelanoma skin cancer
than the general population.
3
Although the reasons for the increased risk in HS are not entirely understood, a known
complication of scarring and chronic inflammation is a Marjolin ulcer (MU), a malignant
degeneration (most commonly SCC) occurring in up to 3.2% of patients with HS.4, 5
Here we report a case of metastatic SCC, believed to be a MU, that developed in an
HS patient being treated with adalimumab.
Case report
A 48-year-old African-American man presented with a longstanding history of HS involving
painful nodules and abscesses in the gluteal and perineal regions. Despite multiple
courses of antibiotics and surgical excision of affected tissue in his left groin
and thigh, the HS lesions were persistent and recurrent. He was started on adalimumab
in November 2015. In November 2016, while still on adalimumab, the patient was given
a clinical diagnosis of pyoderma gangrenosum based on the development of new ulcerated
nodules with a rolled violaceous border at the junction of the left inner thigh and
buttocks, migrating along the scar from his previous surgery. Adalimumab was discontinued
and prednisone and cyclosporine were begun.
In March 2017, the patient was admitted for palpitations and worsening HS (Fig 1).
Bilateral pulmonary emboli were diagnosed, and he was found to have bilateral nodular
airspace opacities on chest radiograph concerning for infection versus malignancy.
Workup found leukocytosis and hypercalcemia. Bronchoscopy with bronchial brushing
and bronchoalveolar lavage, bacterial culture, and fungal and acid-fast bacilli smears
were all negative. Left upper lobe lung biopsy result was negative for malignancy.
Despite antibiotics, repeat computed tomography scans showed increasing opacities
of the lungs along with necrotic pelvic lymph nodes.
Fig 1
Hidradenitis suppurativa with squamous cell carcinoma transformation. Clinical image
taken during most recent hospital admission (28 months after initiation of adalimumab).
The blue arrow indicates chronic scarring, and the yellow arrow signifies indurated
nodules and ulcerations consistent with SCC.
A wound culture of a gluteal ulceration showed growth of pseudomonas. Biopsy of the
left buttock found invasive SCC, negative for human papilloma virus (Fig 2). Biopsies
of a left inguinal mass and iliac ala found invasive SCC involving fibrous tissue
and metastatic SCC in the bone, respectively. A positron emission tomography scan,
performed to stage the malignancy, showed multiple areas of positive lymph nodes in
the pelvis and lungs. It remains unclear if the pulmonary nodules represent metastatic
disease or inflammatory changes from recent pulmonary emboli, as the lung biopsy found
normal lung tissue. The SCC stage was determined to be T2, N3, M1. The patient received
radiation therapy to the left iliac bone but later opted for hospice because of decline
in performance status.
Fig 2
Gluteal ulceration biopsy results show SCC. Punch biopsy specimen taken at the same
time as Fig 1. A, Invasive SCC, well-differentiated without perineural or lymphovascular
invasion. B, HPV p16 negative. (A, Hematoxylin-eosin stain; B, p16 stain; original
magnifications: A, ×40; B, ×10.)
Discussion
HS is a relatively common, chronic, painful skin disease. HS patients may rarely get
SCC, which has a poor prognosis with a 50% 2-year survival rate.
6
The diagnosis of HS relies solely on clinical features and may be delayed an average
of 7 years from the onset of disease.
7
The frequently delayed diagnosis of HS often results in progression to chronic wounds,
which could be a contributory factor in the development of SCC. Although chronic inflammation
from HS likely plays a role in the development of SCCs, other risk factors can contribute
to de novo SCC development. When SCC arises in HS, it is difficult to determine whether
it is de novo, related to the pathogenic features of HS, or if it is part of an MU.
The mean time of symptomatic history of HS before SCC diagnosis is 25 years.
8
Although HS is more common in women, SCC transformation occurs more commonly in men.
6
Body location is another important risk factor, as malignant transformation occurs
almost exclusively in extra-axillary sites, particularly the gluteal region.
8
Additionally, human papilloma virus (HPV) may play a role in the development of de
novo SCC in HS, correlating with higher risk sites of involvement.
8
Smoking is another risk factor for the development of SCC.
8
Immunosuppression may also play a role in the transition of HS to SCC. To the best
of our knowledge, there is only 1 report of an HS patient who had SCC while being
treated with a TNF-α inhibitor (in this case, infliximab).
9
The 2 phase III trials of adalimumab for HS found similar rates of adverse events
in treatment and control groups.
10
However, the relatively small sample size and brief follow-up period limit the ability
of these clinical trials to detect rare events, such as the development of malignancies.
It is controversial as to whether TNF-α inhibitor treatment promotes the development
of skin cancer, as temporality does not necessarily imply causality. It is possible
that our patient might have had SCC before and independent of adalimumab use, because
his disease was longstanding and severe, and we do not have a baseline biopsy. It
is also feasible that the SCC was misdiagnosed as pyoderma gangrenosum in November
2016. Yet the combination of immunosuppressive effects from TNF-α inhibitor use and
independent risk factors (including disease duration, gender, site, HPV status, and
smoking) associated with HS could have played synergistic roles in the development
of this patient's SCC. Although adalimumab is clearly of clinical benefit in the treatment
of HS, the ability of this therapy to prevent complications such as SCC should be
weighed against the possible risk of lowering the threshold for the development of
SCC. We suggest that by better recognizing HS patients who are at higher risk for
the development of SCC, management can be improved leading to increased surveillance
and lower threshold to biopsy with the goal of earlier detection of the rare complication
of SCC.