SKIN 
 

November 2020     Volume 4 Issue 6 
 

Copyright 2020 The National Society for Cutaneous Medicine 620 

SHORT COMMUNICATIONS 
 

 

Eccrine Porocarcinoma Masquerading as Squamous Cell 
Carcinoma 
 
Drew Kuraitis, MD, PhD1, Yong Lee, BS2, Abida Kadi3, Andrea Murina, MD1 
 
1Department of Dermatology, Tulane University, New Orleans, LA 
2Tulane University School of Medicine, Tulane University, New Orleans, LA 
3Department of Pathology, Tulane University, New Orleans, LA 
 

 
 

 
 
A squamoid variant of eccrine 
porocarcinoma (EPC) exists and is often 
misdiagnosed as squamous cell carcinoma 
(SCC) due to clinical and histopathologic 
similarities. In this report, we present two 
cases of presumed SCC based on biopsy 
findings, later diagnosed as EPC after tumor 
excision.  
 

 
 
Case 1 
A 70-year old Caucasian man with a history 
of neurofibromatosis type I presented with 
an asymptomatic hyperkeratotic 
erythematous papule of unknown duration to 
his upper back (Fig 1). Shave biopsy 
revealed invasive, moderately differentiated 
squamous cell carcinoma (SCC; Fig 2A). 
After subsequent excision, the specimen 
was read as moderately-to-poorly 
differentiated carcinoma with eccrine ductal 
differentiation (Fig 2B).  
 
Case 2 
A 64-year old Caucasian man presented 
with a 5-year history of an ulcerated 

hyperkeratotic plaque to his posterior pinna 
(no clinical photo). Shave biopsy revealed 
SCC (Figure 3A). After subsequent excision, 
the specimen was read as poorly 
differentiated porocarcinoma (Figure 3B). 
 
Figure 1. Hyperkeratotic erythematous papule 
diagnosed as squamous cell carcinoma on biopsy, 
later diagnosed as eccrine porocarcinoma after 
excision. 
 

 
 

 
 

In both of these cases, SCC diagnosis was 
rendered based on shave biopsy specimen, 
but later changed to eccrine porocarcinoma 
that after excision. There are reports of a  

INTRODUCTION 

CASE PRESENTATION 

DISCUSSION 



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Figure 2. Tumor diagnosed as squamous cell 
carcinoma on shave biopsy from Case 1 (A). The 
tumor is composed of squamous and basaloid cells 
and shows continuity with the epidermis. No apparent 
poroid differentiation. Tumor re-diagnosed as 
porocarcinoma after excision (B). The tumor exhibits 
anastamosing trabecular growth pattern with ductal 
differentiation within the dermis. The tumor cells have 
pleomorphic and vesicular nuclei. 

 

 
 
squamous variant of EPC histopathologically 
mimics SCC or SCC in situ, although this 
presentation is thought to be quite rare. This 
squamous variant has been characterized in 
a retrospective study of 21 cases.1 Features 
that favor the diagnosis of squamous EPC 
include tumor cells within the dermis in 
anastomosing trabeculae and ductal 
structures lined by tumor cells. Although 
these features were seen on excised 
specimens, the initial shave biopsies 
performed on our patients did not allow for 
assessment of these characteristics, likely 
lending to the diagnosis of SCC. 
 

Accurate diagnosis of EPC is imperative for 
proper medical management. Compared to 
 
Figure 3. Tumor diagnosed as squamous cell 
carcinoma on shave biopsy from Case 2 (A). The 
lesion shows features of moderately differentiated 
invasive squamous cell carcinoma, with 
pleomorphism, increase mitotic activity and 
keratinization. Tumor re-diagnosed as porocarcinoma 
after excision (B). The tumor is composed of basaloid 
cells with intracytoplasmic lumina/duct formation and 
focal keratinization. It has a broadpushing lower 
borders which are sharply delineated. 

 

 



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November 2020     Volume 4 Issue 6 
 

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cutaneous SCC, EPCs have higher rates of 
local recurrence (20%), regional recurrence 
(20%), distant metastasis (12%) and 
mortality (65% with nodal involvement).2 
Non-surgical SCC in situ treatments (topical 
chemotherapy, electrodessication and 
curettage) of EPC masquerading as SCC in 
situ would be insufficient, likely contributing 
to delay of appropriate care and poor 
outcomes. After reviewing our shave biopsy 
and excision specimens, the diagnosis of 
EPC would have been made if the initial 
shave biopsies from both cases had deeper 
dermal sampling.  
 

 
 
We wish to call attention to the existence of 
the squamous EPC variant, in addition to 
highlighting the diagnostic difficulty that 
these lesions may present, as squamous 
EPC variants and squamous cell 
malignancies may have similar clinical and 
histopathologic appearance, especially if 
sampling via shave biopsy provides little 
dermal tissue for examination.  
 
Conflict of Interest Disclosures: None 
 
Funding: None 
 
Corresponding Author: 
Drew Kuraitis 
1430 Tulane Avenue #8036 
New Orleans, LA 70112 
Phone: 504-988-5114 
Email: dkuraiti@tulane.edu 

 
 
References: 
1. Mahomed F, Blok J, Grayson W. The squamous 

variant of eccrine porocarcinoma: a 
clinicopathological study of 21 cases. J Clin 
Pathol. 2008;61(3):361-365. 

2. 2. Snow SN, Reizner GT. Eccrine 
porocarcinoma of the face. J Am Acad Dermatol. 
1992;27(2 Pt 2):306-311. 

CONCLUSION